Help! "An unknown error has occurred."

When pressing F1 over a keyword or selecting "Contents" or "Index" from the Help menu in VB6.0 SP3, I am receiving the following error message : An Unknown error has occurred.

I would rather not uninstall and re-install VB. Anyone know what could be wrong? Everything was fine a week or so ago. I've installed (and since uninstalled) an SQL tool (RapidSQL) which may have done something.

Thanks

Try reinstalling MSDN...not
vbhelp comes from MSDN in vb6
You may have deleted a shared file.

Great! That was it. The last thing the re-install of MSDN did was register the F1 Help Context settings.

Thanks