notepad stuck on one file

When I double click on a .txt file (any .txt file), NotePad opens a file named Program (no extension). Program contains text produced by an Intuit product install. If I rename Program, Windows doesn’t boot the same way and seems to boot incorrectly. I don’t think this effect has anything to do with an Intuit product. The effect began after I tried unsucessfully to install MS Access. Does it mean that my registry is so screwed up that I have to reinstall Windows 98? Or — how does one fix such a problem in the registry short of reinstalling Windows? Be specific.