External USB drive working ok with Karmic (and with other windows computers and with a DVB recorder), but it does not work with lucid in the same computer.
I could give more information: it does not work never in lucid (2.6.32), but always in karmic (2.6.31)

Karmic (boot from DVD, now I have just lucid installed)

Linux ubuntu 2.6.31-14-generic #48-Ubuntu SMP Fri Oct 16 14:05:01 UTC 2009 x86_64 GNU/Linux

[ 2474.890140] usb 2-1: new high speed USB device using ehci_hcd and address 5
[ 2475.042459] usb 2-1: configuration #1 chosen from 1 choice
[ 2475.049496] scsi8 : SCSI emulation for USB Mass Storage devices
[ 2475.049715] usb-storage: device found at 5
[ 2475.049720] usb-storage: waiting for device to settle before scanning
[ 2480.040382] usb-storage: device scan complete
[ 2480.041025] scsi 8:0:0:0: Direct-Access     SAMSUNG  HM500JI               PQ: 0 ANSI: 2 CCS
[ 2480.041908] sd 8:0:0:0: Attached scsi generic sg3 type 0
[ 2480.055180] sd 8:0:0:0: [sdc] 976773168 512-byte logical blocks: (500 GB/465 GiB)
[ 2480.055914] sd 8:0:0:0: [sdc] Write Protect is off
[ 2480.055918] sd 8:0:0:0: [sdc] Mode Sense: 34 00 00 00
[ 2480.055922] sd 8:0:0:0: [sdc] Assuming drive cache: write through
[ 2480.057412] sd 8:0:0:0: [sdc] Assuming drive cache: write through
[ 2480.057418]  sdc: sdc1
[ 2480.096328] sd 8:0:0:0: [sdc] Assuming drive cache: write through
[ 2480.096339] sd 8:0:0:0: [sdc] Attached SCSI disk


Lucid (same disk, same usb connector, same cable ...)It does not work, I am wrinting from karmic, looking in /var/log/messages I see that. I think that dmesg shows other message about I/O error block 0, 1, ... to 7

Mar 18 21:25:47 enrique-laptop kernel: [    0.000000] Linux version 2.6.32-16-generic (buildd@yellow) (gcc version 4.4.3 (Ubuntu 4.4.3-3ubuntu1) ) #25-Ubuntu SMP Tue Mar 9 16:33:12 UTC 2010 (Ubuntu 2.6.32-16.25-generic)


Mar 18 20:30:46 enrique-laptop kernel: [  491.690142] usb 2-2: new high speed USB device using ehci_hcd and address 4
Mar 18 20:30:46 enrique-laptop kernel: [  491.842103] usb 2-2: configuration #1 chosen from 1 choice
Mar 18 20:30:46 enrique-laptop kernel: [  491.851266] scsi7 : SCSI emulation for USB Mass Storage devices
Mar 18 20:30:51 enrique-laptop kernel: [  496.851113] scsi 7:0:0:0: Direct-Access     SAMSUNG  HM500JI               PQ: 0 ANSI: 2 CCS
Mar 18 20:30:51 enrique-laptop kernel: [  496.854597] sd 7:0:0:0: Attached scsi generic sg2 type 0
Mar 18 20:30:51 enrique-laptop kernel: [  496.855288] sd 7:0:0:0: [sdb] 976773168 512-byte logical blocks: (500 GB/465 GiB)
Mar 18 20:30:51 enrique-laptop kernel: [  496.856029] sd 7:0:0:0: [sdb] Write Protect is off
Mar 18 20:30:51 enrique-laptop kernel: [  496.857537]  sdb: sdb1
Mar 18 20:30:51 enrique-laptop kernel: [  496.863524] sd 7:0:0:0: [sdb] Attached SCSI disk
Mar 18 20:30:59 enrique-laptop kernel: [  504.160133] usb 2-2: reset high speed USB device using ehci_hcd and address 4
Mar 18 20:31:08 enrique-laptop kernel: [  513.160121] usb 2-2: reset high speed USB device using ehci_hcd and address 4
Mar 18 20:31:09 enrique-laptop kernel: [  514.648447] sd 7:0:0:0: [sdb] Unhandled sense code
Mar 18 20:31:09 enrique-laptop kernel: [  514.648457] sd 7:0:0:0: [sdb] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Mar 18 20:31:09 enrique-laptop kernel: [  514.648466] sd 7:0:0:0: [sdb] Sense Key : Medium Error [current] 
Mar 18 20:31:09 enrique-laptop kernel: [  514.648475] sd 7:0:0:0: [sdb] Add. Sense: Unrecovered read error
Mar 18 20:31:09 enrique-laptop kernel: [  514.648485] sd 7:0:0:0: [sdb] CDB: Read(10): 28 00 00 00 00 01 00 00 08 00
Mar 18 20:31:09 enrique-laptop kernel: [  514.648513] __ratelimit: 12 callbacks suppressed