Are you trying to install a Zip drive? If so go to the manufacturers website and download the drivers.

Have you added any new cards or anything to the machine lately. What you have described can be cause by your power supply not supplying enough voltage for everything on the machine.

no

Check device manager and see if everything looks ok there.

Anyone can change one. There should be a few screws on the bottom with a keyboard picture next to them. There may be some tabs on the keyboard itself, not sure with sony. Then it's should just be...

Sounds like your ribbon cable has been damaged. You should replace the keyboard.