Have this problem since my Jaunty upgrade. Upgraded from existing intrepid install. Config identical to hostname config. In fact I can still boot into a snapshot of the pre-upgrade intrepid (have backups, at all times). Immediately exiting the busybox shell works all the time. 

Did anyone investigate whether all reporting users use LVM? It seemed so to me. Note: LVM, not RAID per se. (I use LVM with no encryption, striping, raid or whatever. Plain LVM+xfs for ease of administration).

Note that I also have the same problem now when booting into that intrepid install (using the same kernel/initramfs 2.6.28-11-generic). I can guarantee (lvm snapshot isolation) that it wasn't touched *EXCEPT* for the shared /boot partition. This narrows it to a kernel/initramfs change in the kernel for Jaunty Beta (09 aprl 2009) vs. intrepid latest kernel? 

I do recall that there had been a kernel upgrade in the 'regular' updates for my intrepid box yesterday. I *have* rebooted the intrepid box without problems *after* that particular kernel update but *before* the dist-upgrade to Jaunty. I have *not* seen a smooth reboot since dist-upgrading to Jaunty.

I did also note that the dist-upgrade seems to use a deviant method of rebooting after install? It seems to bypass the BIOS and instead invoke the boot-loader code directly (no BIOS POST screens appeared). This might not play well with my hdparm settings since I auto-suspend most of my disks after some 15 seconds and this easily leads to timing issues when disks need to be awoken. However, the same issues also arise when doing cold/BIOS boots.

Here is my system details:
MOBO Asus P5b Deluxe Wifi
root@hostname:~# uname -a
Linux hostname.sehe.nl 2.6.28-11-generic #41-Ubuntu SMP Wed Apr 8 04:38:53 UTC 2009 i686 GNU/Linux
root@hostname:~# lvm version
  LVM version:     2.02.39 (2008-06-27)
  Library version: 1.02.27 (2008-06-25)
  Driver version:  4.14.0
root@hostname:~# lspci
00:00.0 Host bridge: Intel Corporation 82P965/G965 Memory Controller Hub (rev 02)
00:01.0 PCI bridge: Intel Corporation 82P965/G965 PCI Express Root Port (rev 02)
00:1a.0 USB Controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #4 (rev 02)
00:1a.1 USB Controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #5 (rev 02)
00:1a.7 USB Controller: Intel Corporation 82801H (ICH8 Family) USB2 EHCI Controller #2 (rev 02)
00:1b.0 Audio device: Intel Corporation 82801H (ICH8 Family) HD Audio Controller (rev 02)
00:1c.0 PCI bridge: Intel Corporation 82801H (ICH8 Family) PCI Express Port 1 (rev 02)
00:1c.4 PCI bridge: Intel Corporation 82801H (ICH8 Family) PCI Express Port 5 (rev 02)
00:1c.5 PCI bridge: Intel Corporation 82801H (ICH8 Family) PCI Express Port 6 (rev 02)
00:1d.0 USB Controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #1 (rev 02)
00:1d.1 USB Controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #2 (rev 02)
00:1d.2 USB Controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #3 (rev 02)
00:1d.7 USB Controller: Intel Corporation 82801H (ICH8 Family) USB2 EHCI Controller #1 (rev 02)
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev f2)
00:1f.0 ISA bridge: Intel Corporation 82801HB/HR (ICH8/R) LPC Interface Controller (rev 02)
00:1f.2 IDE interface: Intel Corporation 82801H (ICH8 Family) 4 port SATA IDE Controller (rev 02)
00:1f.3 SMBus: Intel Corporation 82801H (ICH8 Family) SMBus Controller (rev 02)
00:1f.5 IDE interface: Intel Corporation 82801H (ICH8 Family) 2 port SATA IDE Controller (rev 02)
01:00.0 VGA compatible controller: nVidia Corporation G70 [GeForce 7600 GS] (rev a1)
02:00.0 Ethernet controller: Marvell Technology Group Ltd. 88E8056 PCI-E Gigabit Ethernet Controller (rev 12)
03:00.0 SATA controller: JMicron Technologies, Inc. JMicron 20360/20363 AHCI Controller (rev 02)
03:00.1 IDE interface: JMicron Technologies, Inc. JMicron 20360/20363 AHCI Controller (rev 02)
05:03.0 FireWire (IEEE 1394): Texas Instruments TSB43AB22/A IEEE-1394a-2000 Controller (PHY/Link)
05:04.0 Ethernet controller: Marvell Technology Group Ltd. 88E8001 Gigabit Ethernet Controller (rev 14)