This is the third dying Seagate Barracuda IV I have had the misfortune of owning. 80 Gbyte Model ST380021A.
Symptoms:
Data Corruption, System Lockup(keyboard not responding), Programs running flakey, and a short access noise resembling a high pitch vibration/rattle.
The last drive developed a serious bad sector problem. This drive does not show any signs of bad sectors, SeaTools reports the drive is mechanicaly and electronicly sound. I suspect a full disc scan would turn up issues.

Now for the Rant
Friday evening I went to Best Buy to pick up the cheapest(Not Seagate) drive they have to hold this system over till a new machine is built. Any 40, 80, even 160 GB drive, ATA(EIDE) will do.
No ATA drives on the shelve. Several Sales tags but no ATA drives. The clerk said a truck shipment gets unloaded every Friday night. They should be on the shelve Saturday.
Saturday, still no drives. Another kid tells me they can not get any more ATA drives. ? ? ?
I considered buying the external USB drive and using its drive. I go by Circuit City and the same deal. They have one drive, a 320GB WD for $150. Now I am considering a SATA Card and Drive.
New Egg, two days and $100 later, a 320GB WD drive has cured the issue.

I looked at the Seagate Perpendicular Recording drives at New Egg but read some frightening feedback. I think I will avoid Seagate Drives.

Long Live Western Digital!