PC Stats posted a guide about fixing a 1TB hard drive that suddenly changes to 32MB in size.

The loss of factory hard drive capacity seems to be an increasingly common occurrence with very large capacitym 1TB hard drives, but it's not specific to any one hard drive manufacturer. It can happen to brand new drives or existing hard drives full of data. In either case the data portion of the drive isn't generally affected. If a new or existing hard drive in your computer suddenly pops up with a capacity of 32MB, or another value equally small compared to the true drive size, don't freak out, the data should still be there. Here's what typically happens; a large capacity hard drive of between 500GB, 750GB, 1TB and 1.5TB suddenly appears to loose most of its capacity for no apparent reason. In many situations the capacity of the hard drive shrinks to 0.0GB or 32MB (and occasionally 32GB) and becomes inaccessible to the Windows Vista.

What's happening, to put it simply, is that the portion of the hard drive responsible for telling the computer how big it is, is mis-reporting that value. We don't have a good technical explanation for what causes this issue to randomly strike PC users, but suffice to say a portion of the drive firmware known as the LBA48, HPA and DCO records becomes corrupted.

Our experience with the loss of factory hard drive capacity bug came whilst setting up a new PC with two fresh 1TB Western Digital Caviar Black SATA hard drives. Both SATA drives had been formatted and were working fine. After hard power-off reboot one of the 1TB disks suddenly became a lot smaller than it actually was.

Instead of reporting it's true capacity of 1000GB, or 1TeraByte, the Western Digital Caviar Black Edition SATA hard drive appeared to both the Microsoft Windows Vista operating system and the motherboard BIOS with a false capacity of 32MB. Somehow 999.968GB of storage space had disappeared into thin air! The new drive capacity of 32MB just seemed a little too specific to be random, so we did a little investigating. What we found is that quite a few PC users have experienced the exact same situation - a new or existing large capacity hard drive suddenly looks to the computer like it's only 32MB, or 32GB in size. If the hard drive was previously filled with 1000GB worth of data you can imagine the shock of seeing it reduced to 32MB! Incidently, the 32MB figure seems to be drawn from the hard drives' onboard cache memory.

The Seagate's bug was worse ....