Partitions "disappearing"

[j00ed]

First, a little bit of info about my system.
I installed Fedora 11, having switched from Xubuntu 9.04. I have two hard drives, one that is fully occupied by Fedora and one that was two partitions: a 50GB NTFS partition (/dev/sdb1) with Windows XP installed and a 950GB JFS (/dev/sdb2) partition for large file storage. Both are recently bought Western Digital drives.

I booted Fedora 11 this morning and the partitions of the second hard drive had, quite simply, 'disappeared' and replaced with 31.38MiB of unallocated space (or at least that's what GParted says). Note that Fedora didn't have any kind of problems with my hard drives the day before. In any case, I've already tried these:

~booted from Ubuntu LiveCD and Parted Magic, got the same result
~tried a different Kernel version (as I recently changed that), got the same result
~tried mounting JFS via command line, and that was expectedly impossible since there was no /dev/sdb2
~analysed /dev/sdb with testdisk 6.11.3, which "discovered" an NTFS partition with a Warning: "Bad ending cylinder (CHS and LBA don't match)" and "No EXT2, JFS, Reiser, cramfs or XFS marker" and also took notice of the drive's unnaturally small size (31.38MiB)
~thoroughly cleaned everything there is to be cleaned as well as reconnected my hard drives, so as to get rid of dust (which generally causes everything to malfunction)
~used lshw, which discovered the missing partitions, with correct sizes, although it also thinks the entire hard drive is 31MiB big

I have more or less run out of ideas. I can live without /dev/sdb2, but I really don't feel very good with about 400GBs of non-backed-up data vanishing into thin air.

So, any suggestions?

[Lostfarmer]

I sespect if you look in the bios the hdd is not being detected for the correct size. Problem could be:
1) bad/loose data cable to hdd, reset both ends/replace
2) bad hdd, test with manufacture's test program
3) bad motherboard /bios battery bad
Try going into bios and tell it to redetect the hdd.

[j00ed]

Solved. I had to use hdparm -N#sectors and disable HPA. The problem was caused by using init 3 or the NVIDIA drivers.