I haven't seen this particular behavior with the VB6 IDE though I have seen similar with other products. It sounds like the installation (VS6) is missing a component somewhere which is causing it to fire up the Windows installer. I'd suggest you remove VS6 altogether, do a clean up with CCleaner and re-install VS6 from scratch.

You might also want to get a copy of the Microsoft Windows Installer Clean-Up utility (Google it and you should find it).

-Max