Help! I'm Getting a "Firefox must close" error message, but?

The message pops up and says “sorry Firefox has encounterd a problem and needs to close”. Trouble is, I am not using Firefox! I did install it at one time but went back to IE. I removed the Firefox program at least a year ago. When this message first popped up recently I checked and neither Mozilla nor Firefox was in the list of programs, but I did a seach and found a few Firefox files which I deleted. I am still getting the error message. Anyone got an idea what to do?