Let's start from broad to narrow.
Obviously, the file is missing from your computer. Let's start by first checking the "run on start" feature in the profile manager and look in your autoexec.bat. Then look in the startup menu folder for the programs that are running.
After that you have investigated that with no joy do a search on your 'registery' for a orphan entry. There some tools available for this on the windows CD usually. You can also find registry tools online.
If all these approaches fail then I would go through each program installed to see if they are calling this file. Check first the programs on startup.
If that fails then check all your cd's for the file.
if that fails you'll be shit out of luck. Do the infamous, wipe the drive, and re-install.
if that fails then complain to Bill Gates!