I could not access my computer yesterday, so I started in Safe Mode and did a system restore to a previous point. It then seemed to work fine. Today I did a scan and fix using Netcom's PC Cleaner. Afterwards, whenever I try opening a Word document or browser (IE or Mozilla), the Windows Installer pops up with a "preparing to install" message. The browser eventually appears, but I cannot open Word or "Help and Support" ( I was going to try and do another system restore).

Can anyone think of what may be the cause and solution?

I was able to restore to an earlier point (using search to access the system restore wizard), and this resolved my problem.

Did you run your cleaning program before the first problem? It sounds like the second fault was caused by your cleaning program removing needed files.

Joe