After installing the patch, the "crashed on signal 11" errors seem to have disappeared, however printing still isn't working for me:
(I removed the existing printer, re-added it and then tried to print some document)

E [25/Apr/2006:09:08:26 +0200] cupsdAuthorize: Local authentication certificate not found!
E [25/Apr/2006:09:08:26 +0200] cupsdAuthorize: Local authentication certificate not found!
E [25/Apr/2006:09:08:26 +0200] cupsdAuthorize: Local authentication certificate not found!
E [25/Apr/2006:09:08:30 +0200] cupsdAuthorize: Local authentication certificate not found!
E [25/Apr/2006:09:08:30 +0200] CUPS-Delete-Printer: Unauthorized
E [25/Apr/2006:09:10:12 +0200] CUPS-Add-Modify-Printer: Unauthorized
E [25/Apr/2006:09:11:44 +0200] [Job 6] Session setup failed: NT_STATUS_LOGON_FAILURE
E [25/Apr/2006:09:11:44 +0200] [Job 6] No ticket cache found for userid=1000
E [25/Apr/2006:09:11:44 +0200] [Job 6] Can not get the ticket cache for gds
E [25/Apr/2006:09:11:44 +0200] [Job 6] perl: warning: Setting locale failed.
E [25/Apr/2006:09:11:44 +0200] [Job 6] perl: warning: Please check that your locale settings:
E [25/Apr/2006:09:11:44 +0200] [Job 6] LANGUAGE = (unset),
E [25/Apr/2006:09:11:44 +0200] [Job 6] LC_ALL = (unset),
E [25/Apr/2006:09:11:44 +0200] [Job 6] LANG = "en_US"
E [25/Apr/2006:09:11:44 +0200] [Job 6] are supported and installed on your system.
E [25/Apr/2006:09:11:44 +0200] [Job 6] perl: warning: Falling back to the standard locale ("C").
E [25/Apr/2006:09:11:44 +0200] [Job 6] Session setup failed: NT_STATUS_LOGON_FAILURE
E [25/Apr/2006:09:11:45 +0200] [Job 6] Tree connect failed (NT_STATUS_ACCESS_DENIED)
E [25/Apr/2006:09:11:45 +0200] [Job 6] Unable to connect to CIFS host, will retry in 60 seconds...
E [25/Apr/2006:09:11:45 +0200] [Job 6] foomatic-rip version $Revision: 3.43.2.15 $ running...
E [25/Apr/2006:09:11:45 +0200] [Job 6] Parsing PPD file ...
E [25/Apr/2006:09:11:45 +0200] [Job 6] *cupsFilter: "application/vnd.cups-postscript 0 foomatic-rip"
E [25/Apr/2006:09:11:45 +0200] [Job 6] Added option ColorSpace
E [25/Apr/2006:09:11:45 +0200] [Job 6] Added option PageSize
E [25/Apr/2006:09:11:45 +0200] [Job 6] Added option PageRegion
E [25/Apr/2006:09:11:45 +0200] [Job 6] Added option ImageableArea
E [25/Apr/2006:09:11:45 +0200] [Job 6] Added option PaperDimension
E [25/Apr/2006:09:11:45 +0200] [Job 6] Added option InputSlot
E [25/Apr/2006:09:11:45 +0200] [Job 6] Added option MediaType
E [25/Apr/2006:09:11:45 +0200] [Job 6] Added option Resolution
E [25/Apr/2006:09:11:45 +0200] [Job 6] Added option EconoMode
E [25/Apr/2006:09:11:45 +0200] [Job 6] Added option HalftoningAlgorithm
E [25/Apr/2006:09:11:45 +0200] [Job 6] Added option Font
E [25/Apr/2006:09:11:45 +0200] [Job 6]
E [25/Apr/2006:09:11:45 +0200] [Job 6] Parameter Summary
E [25/Apr/2006:09:11:45 +0200] [Job 6] -----------------
E [25/Apr/2006:09:11:45 +0200] [Job 6]
E [25/Apr/2006:09:11:45 +0200] [Job 6] Spooler: cups
E [25/Apr/2006:09:11:45 +0200] [Job 6] Printer: HL-1250
E [25/Apr/2006:09:11:45 +0200] [Job 6] PPD file: /etc/cups/ppd/HL-1250.ppd
E [25/Apr/2006:09:11:45 +0200] [Job 6] Printer model: Brother HL-1250 Foomatic/hl1250 (recommended)
E [25/Apr/2006:09:11:45 +0200] [Job 6] Job title: stdin
E [25/Apr/2006:09:11:45 +0200] [Job 6] File(s) to be printed:
E [25/Apr/2006:09:11:45 +0200] [Job 6] <STDIN>
E [25/Apr/2006:09:11:45 +0200] [Job 6]
E [25/Apr/2006:09:11:45 +0200] [Job 6] GhostScript extra search path ('GS_LIB'): /usr/share/cups/fonts
E [25/Apr/2006:09:11:45 +0200] [Job 6] Pondering option 'PageSize=A4'
E [25/Apr/2006:09:11:45 +0200] [Job 6] Pondering option 'PageRegion=A4'
E [25/Apr/2006:09:11:45 +0200] [Job 6] Pondering option 'Resolution=600x600dpi'
E [25/Apr/2006:09:11:45 +0200] [Job 6] Pondering option 'job-uuid=urn:uuid:158feb20-61be-3b47-7a82-cd9ec68d039f'
E [25/Apr/2006:09:11:45 +0200] [Job 6] Unknown option job-uuid=urn:uuid:158feb20-61be-3b47-7a82-cd9ec68d039f.
E [25/Apr/2006:09:11:45 +0200] [Job 6]
E [25/Apr/2006:09:11:45 +0200] [Job 6] ================================================
E [25/Apr/2006:09:11:45 +0200] [Job 6]
E [25/Apr/2006:09:11:45 +0200] [Job 6] File: <STDIN>
E [25/Apr/2006:09:11:45 +0200] [Job 6]
E [25/Apr/2006:09:11:45 +0200] [Job 6] ================================================
E [25/Apr/2006:09:11:45 +0200] [Job 6]
E [25/Apr/2006:09:11:45 +0200] [Job 6] Reading PostScript input ...
E [25/Apr/2006:09:11:45 +0200] [Job 6] --> This document is DSC-conforming!
E [25/Apr/2006:09:11:45 +0200] [Job 6]
E [25/Apr/2006:09:11:45 +0200] [Job 6] -----------
E [25/Apr/2006:09:11:45 +0200] [Job 6] Found: %%BeginProlog
E [25/Apr/2006:09:11:45 +0200] [Job 6] Found: %%EndProlog
E [25/Apr/2006:09:11:45 +0200] [Job 6]
E [25/Apr/2006:09:11:45 +0200] [Job 6] -----------
E [25/Apr/2006:09:11:45 +0200] [Job 6] Found: %%BeginSetup
E [25/Apr/2006:09:11:45 +0200] [Job 6] Found: %%BeginFeature: *PageRegion A4
E [25/Apr/2006:09:11:45 +0200] [Job 6] Option: PageRegion=A4 --> Option will be set by PostScript interpreter
E [25/Apr/2006:09:11:45 +0200] [Job 6] Found: %%BeginFeature: *MediaType Plain
E [25/Apr/2006:09:11:45 +0200] [Job 6] Option: MediaType=Plain --> Setting option
E [25/Apr/2006:09:11:45 +0200] [Job 6] Found: %% FoomaticRIPOptionSetting: MediaType=Plain
E [25/Apr/2006:09:11:45 +0200] [Job 6] Option: MediaType=Plain --> Setting option
E [25/Apr/2006:09:11:45 +0200] [Job 6] Found: %%BeginFeature: *EconoMode off
E [25/Apr/2006:09:11:45 +0200] [Job 6] Option: EconoMode=off --> Setting option
E [25/Apr/2006:09:11:45 +0200] [Job 6] Found: %% FoomaticRIPOptionSetting: EconoMode=off
E [25/Apr/2006:09:11:45 +0200] [Job 6] Option: EconoMode=off --> Setting option
E [25/Apr/2006:09:11:45 +0200] [Job 6] Found: %%BeginFeature: *InputSlot auto
E [25/Apr/2006:09:11:45 +0200] [Job 6] Option: InputSlot=auto --> Setting option
E [25/Apr/2006:09:11:45 +0200] [Job 6] Found: %% FoomaticRIPOptionSetting: InputSlot=auto
E [25/Apr/2006:09:11:45 +0200] [Job 6] Option: InputSlot=auto --> Setting option
E [25/Apr/2006:09:11:45 +0200] [Job 6] Found: %%BeginFeature: *Resolution 600x600dpi
E [25/Apr/2006:09:11:45 +0200] [Job 6] Option: Resolution=600x600dpi --> Option will be set by PostScript interpreter
E [25/Apr/2006:09:11:45 +0200] [Job 6] Found: %%EndSetup
E [25/Apr/2006:09:11:45 +0200] [Job 6] Inserting PostScript code for CUPS' page accounting
E [25/Apr/2006:09:11:45 +0200] [Job 6]
E [25/Apr/2006:09:11:45 +0200] [Job 6] -----------
E [25/Apr/2006:09:11:45 +0200] [Job 6] New page:  1 1
E [25/Apr/2006:09:11:45 +0200] [Job 6] Inserting option code into "PageSetup" section.
E [25/Apr/2006:09:11:45 +0200] [Job 6]
E [25/Apr/2006:09:11:45 +0200] [Job 6] Found: %%BeginPageSetup
E [25/Apr/2006:09:11:45 +0200] [Job 6] Found: %%EndPageSetup
E [25/Apr/2006:09:11:45 +0200] [Job 6] End of page header
E [25/Apr/2006:09:11:45 +0200] [Job 6] Flushing FIFO.
E [25/Apr/2006:09:11:45 +0200] [Job 6]
E [25/Apr/2006:09:11:45 +0200] [Job 6] Starting renderer
E [25/Apr/2006:09:11:45 +0200] [Job 6] JCL: %-12345X@PJL
E [25/Apr/2006:09:11:45 +0200] [Job 6] @PJL SET MEDIATYPE=REGULAR
E [25/Apr/2006:09:11:45 +0200] [Job 6] <job data>
E [25/Apr/2006:09:11:45 +0200] [Job 6] %-12345X@PJL RESET
E [25/Apr/2006:09:11:45 +0200] [Job 6]
E [25/Apr/2006:09:11:45 +0200] [Job 6] renderer PID kid4=6760
E [25/Apr/2006:09:11:45 +0200] [Job 6] renderer command: gs -q -dBATCH -dPARANOIDSAFER -dNOPAUSE -sDEVICE=hl1250 -dEconoMode=0 -dSourceTray=0 -sOutputFile=- -
E [25/Apr/2006:09:11:45 +0200] [Job 6] perl: warning: Setting locale failed.
E [25/Apr/2006:09:11:45 +0200] [Job 6] perl: warning: Please check that your locale settings:
E [25/Apr/2006:09:11:45 +0200] [Job 6] LANGUAGE = (unset),
E [25/Apr/2006:09:11:45 +0200] [Job 6] LC_ALL = (unset),
E [25/Apr/2006:09:11:45 +0200] [Job 6] LANG = "en_US"
E [25/Apr/2006:09:11:45 +0200] [Job 6] are supported and installed on your system.
E [25/Apr/2006:09:11:45 +0200] [Job 6] perl: warning: Falling back to the standard locale ("C").
E [25/Apr/2006:09:11:45 +0200] [Job 6] foomatic-gswrapper: gs '-dBATCH' '-dPARANOIDSAFER' '-dNOPAUSE' '-sDEVICE=hl1250' '-dEconoMode=0' '-dSourceTray=0' '-sOutputFile=/dev/fd/3' '/dev/fd/0' 3>&1 1>&2
E [25/Apr/2006:09:11:45 +0200] [Job 6] ESP Ghostscript 815.01 (2005-09-22)
E [25/Apr/2006:09:11:45 +0200] [Job 6] Copyright (C) 2004 artofcode LLC, Benicia, CA.  All rights reserved.
E [25/Apr/2006:09:11:45 +0200] [Job 6] This software comes with NO WARRANTY: see the file PUBLIC for details.
E [25/Apr/2006:09:11:46 +0200] [Job 6]
E [25/Apr/2006:09:11:46 +0200] [Job 6] Closing renderer
E [25/Apr/2006:09:11:46 +0200] [Job 6] tail process done writing data to STDOUT
E [25/Apr/2006:09:11:46 +0200] [Job 6] KID4 finished
E [25/Apr/2006:09:11:46 +0200] [Job 6] KID3 finished
E [25/Apr/2006:09:11:46 +0200] [Job 6] KID3 exited with status 0
E [25/Apr/2006:09:11:46 +0200] [Job 6] KID4 exited with status 0
E [25/Apr/2006:09:11:46 +0200] [Job 6] Renderer exit stat: 0
E [25/Apr/2006:09:11:46 +0200] [Job 6] Renderer process finished
E [25/Apr/2006:09:11:46 +0200] [Job 6]
E [25/Apr/2006:09:11:46 +0200] [Job 6] Closing foomatic-rip.
E [25/Apr/2006:09:12:45 +0200] [Job 6] Session setup failed: NT_STATUS_LOGON_FAILURE
E [25/Apr/2006:09:12:45 +0200] [Job 6] No ticket cache found for userid=1000
E [25/Apr/2006:09:12:45 +0200] [Job 6] Can not get the ticket cache for gds
E [25/Apr/2006:09:12:45 +0200] [Job 6] Session setup failed: NT_STATUS_LOGON_FAILURE
E [25/Apr/2006:09:12:45 +0200] [Job 6] Tree connect failed (NT_STATUS_ACCESS_DENIED)
E [25/Apr/2006:09:12:45 +0200] [Job 6] Unable to connect to CIFS host, will retry in 60 seconds...

I'm sure username and password are correct as well as the host etc.
Connecting to the server through samba from within Nautilus gives no problems with the same credentials.

One thing I noticed is that the username was disappeared from the printer properties right after having added the printer initially.
Trying to make modifications through Printers -> Properties doesn't seem to work !
Changing DPI, paper size, username, etc has no effect as everything gets reset when clicking the Close button.
Maybe this is related to

CUPS-Add-Modify-Printer: Unauthorized

in the cups error log ?