My thoughts:
1. I absolutely would leave it on. There is NO advantage to turning it off.
2. To find the original Users and Installation guides for your drive, go www.seagate.com and enter the drives' model number (from the label on it's top) in the "Enter model #" box. Shows you all kinds of...
You also might try
1. Use the defragger which comes with Windows (2K and XP) to see if the drive still makes the same sound. This would isolate the problem to DiskKeeper Lite behavior, not the disk going bad.
2. I also think the suggestion (made above) to run the disk manufacturer's diagnostic...
My suspision is the most likely cause of your problem is driver and/or BIOS related. I would:
1. Verify you have anti-virus software installed and have performed a full system virus scan to be sure *thats* not an underlying issue (I recommend Norton Systemworks).
2. Go to your motherboard's...