Have you ever installed a program and then when you uninstall, it keeps the files behind. Or does not do the uninstallation at all? What causes this and what can be done to make sure your computer is clean of the files?

Have you done an AV scan? It's probably a good idea, just in case. Scans for spy/adware also wouldn't hurt.

Was the program one that you'd downloaded using p2p?

You could try deleting in safe mode. Or use the computer's search to look for all files & folders associated with the program, then delete everything that way. If files are stubborn, you might need some tools to help remove them. Check out this thread for more info. I've used both Unlocker & DelinvFile & they work well.
http://www.gnutellaforums.com/showpo...35&postcount=2

Also, if you are interested, you could use a program like Total Uninstall. You run it prior to installing a program & you can use it to remove the program as well. It does take a few moments longer, but when you uninstall a program with it, it will let you know if there is anything left behind afterwards.

Free version here:
http://www.aplusfreeware.com/categor...il/uninst.html