Firefox issues...and I don't have Firefox!

I asked a similar question a few weeks ago, but now I have a different problem. I keep getting a Firefox error message that says that Firefox has encountered a problem and needs to close. Well, that’s fine, except I don’t have Firefox installed. I used Firefox over a year ago, but it never worked correctly so I removed it. All of the sudden I’ve started to get the error messages. I did a search and found some Firefox files and I deleted them. Everything is fine for a few days and then I get hundereds of error messages. I do a search and find the same files again. Again I delete them. Every two or three days they come back. My question: How are these files re-appearing? How do I stop it from happening? Should I reinstall Firefox and then remove it again hoping all traces will be gone for good? It’s so odd. Help?