Can't access boot partition

[Guest]

I'm looking at a Toshiba 60GB HD from an Acer notebook. (Aspire 2000)
It wil not boot-the HD just continually cycles.
I connected it to my XP Pro machine via USB, and the primary partition shows
as unformatted. I get event ID 51 in event viewer(Replace hardware).
I cannot format it in Disk manager (Format failed).
I ordered a new HD, then started playing with it and discovered it would
format if I tried My Computer. (This HD has 4 partitions, one of which is
unformatted, one is 9GB of Acer files, and a smaller one, also unformatted.
The 4th is the primary.
I'm using the Acer Recovery CD at the moment, and it seems to be working.
What happened to this HD?
If the recovery completes, should I continue to use this HD, or should I
consider it unreliable, and install the new one?
TIA.

 

[Guest]

Follow-up:
The recovery completed successfully and a diagnostic test shows no errors.
I'd appreciate any input on the cause of this crash.