I'm stuck trying to recover my computer, please help!

My system used to have two disks: an older IDE disk, with Windows XP and an old Ubuntu installation, and a newer SATA disk, with a current Ubuntu. The older one started to give errors, but I wasn't too worried, since I hardly ever use Windows. But then the kernel upgrade started to take forever, because it got lots of errors while scanning the old disk.

So I decided to remove the IDE disk and keep just the SATA. Since then, I haven't been able to boot anymore. I first thought that the BIOS was still looking for something on the IDE that didn't exist any more, so I tried AHCI mode. It didn't work either, and I have been trying several variants on the BIOS, to no avail. The BIOS always detects the SATA DVD, but the hard disk isn't always detected.

I thought that the SATA disk probably didn't have a bootloader, so I tried booting with a Kubuntu live CD to run boot-repair and make it bootable. It took over an hour to boot, and even then, it didn't detect the hard disk. I have booted with System Rescue CD and booting takes a little shorter, but still over half an hour.

The Live CD kept giving errors like:

Code:
timeout: killing '/sbin/blkid -o udev -p ' ....

System Rescue CD gives the following errors while booting

Code:
udevadm settle - timeout of 180 seconds reached, the event queue contains:
/sys/devices/pci0000:00/0000:00:1f.2/host4/target4:0:0/4:0:0:0/block/sda (1096)
/sys/devices/pci0000:00/0000:00:1f.2/host4/target4:0:0/4:0:0:0/block/sda/sda1 (1097)
/sys/devices/pci0000:00/0000:00:1f.2/host4/target4:0:0/4:0:0:0/block/sda/sda2 (1098)
/sys/devices/pci0000:00/0000:00:1f.2/host4/target4:0:0/4:0:0:0/block/sda/sda3 (1099)
/sys/devices/pci0000:00/0000:00:1f.2/host4/target4:0:0/4:0:0:0/block/sda/sda4 (1100)
/sys/devices/pci0000:00/0000:00:1f.2/host4/target4:0:0/4:0:0:0/block/sda/sda5 (1101)
/sys/devices/pci0000:00/0000:00:1f.2/host4/target4:0:0/4:0:0:0/block/sda/sda6 (1102)
/sys/devices/pci0000:00/0000:00:1f.2/host4/target4:0:0/4:0:0:0/block/sda (1337)
udevd[162]; worker [189] unexpectedly returned with status 0x0100

After booting with System Rescue CD, I have managed to mount my home partition (it took a long time to mount, too), and I can access the files, so the disk seems to be good. Any ideas on what to do next? The motherboard is an Asus P5QC. I'm worried that the disk controller may have failed.