Hard Drive Madness - Please help!

Within the last 10 days, I’ve experienced a lifetime’s worth of hard drive problems!

Summary:
(1): Some hard drives show more storage than physical capacity!

(2): Some hard drives not seen at all on the same SATA port that other drives work fine on!

(3): Partitions disappear, are then restored, then disappear again!

(4): Similar problems now on two separate XP Pro/SP3 computers!

Details:

(1): (a): One 1.5 TB WD drive shows nearly 2 TB already stored there (no compressed partitions, no RAID).  All partitions are NTFS.

(b): One 1.0 TB WD drive shows nearly 1.5 TB already stored there (same as above).

What the heck is going on?  This only started recently.

(2): Starting about a week ago, some hard drives were seen on the system, but were falsely reported to be completely unallocated.  I was able to recover the partitions and data, but as of today, some of those drives aren’t seen at all! (examined by Acronis Disk Director 11, XP Disk Management, XP Device Manager).

(3): I’ve seen a couple of disks “lose” all it’s partitions, but I was able to recover everything with Acronis Disk Director 11’s Recovery tool.  Later, the partitions disappeared again!

(4): At first, I was only having problems on one of my computers.  Now I’m having very similar problems on two XP Pro/SP3 systems.  It looks like the problems are spreading!  I ran Kaspersky 2010 KAV on the first computer, searching for root kits and all malware at absolute maximum settings, but it could find no infections.

Can some kind of malware cause these kinds of problem?  If so, what tool should I run to get rid of it?

Aaargh!  Please - Help!