Data Corruption: What Happens, and How Can You Fix It?

My computer is making a loud clicking noise--usually when just turning it on--and has been freezing up and crashing.
Our problems started when we tried to transfer music files from my Tascam digital 8-track recorder to the computer. One mistake was when we disconnected the USB cable before properly exiting the program. We were supposed to drag the tascam icon to the trash before disconnecting the USB from the computer. The Tascam manual and a warning sign that pops up both say that data may have been corrupted.
Our songs show up on the computer without a problem, but ever since then, we have been having all of the problems with clicking and crashing.
I'm not sure if the other problem I am having is related to this. I accidently deleted my song from the tascam's compact flash drive, and wanted to import it from the computer. However, every time I try to do this, the computer shows that it's copying the file, but the Tascam always says, "file not found." Could this be due to the data corruption?
Any suggestions will be greatly appreciated.

That clicking sound is typically one of the first clues of a failing hard drive. (At least on those that don't just totally die.) This will cause freezes, crashes and not being able to find files in some locations on the drive.

If you don't have a back up of your data, I would suggest doing so promptly and replacing the drive as soon as you can.

Buy an external hard drive immediately. If you get a 500GB one, you should be safe.

Yes it could be due to your disconnecting without ragging to the trash, although as bobtomay says sounds like HDD dying. If you have the OS install disc, boot from that and run Repair Disc and see what is reported?

Also Smart Reporter v.2.3.9 is a great little utility which places an icon on the Menu bar which advises state of your drive.

Seems like a fan problem to me. I'm probably wrong, though.