Had a similar situation, yesterday.
Boss bought a 1TB WD drive and an external enclosure.
It connects via eSATA, or USB.
His computer runs Vista.
Put it together for him, hooked it up using eSATA connection, and Vista wouldn't recognize it.
Tried the USB connection, and it was recognized.
Initialized the drive, and set it to do a full format, using NTFS file system.
After 45 minutes, he came and told me it was through.
That didn't sound right.
45 minutes, for a 1TB drive?
Went and checked it, and saw it was formatted to RAW.
Tried to re-format, and it hung up.
Since I'm not too familiar with Vista, I thought I might be doing something wrong.
Took the drive home, to hook it up to my XP box.
Connected using eSATA, initialized, and started formatting.
3 hrs. and 15 mins. later (that's more like it )
, I had a fully functional, NTFS formatted drive.
Brought it back this morning, hooked it up, it was recognized, and is working perfectly.
I wonder if it's Vista, that has the problem.