I am running Windows XP and keeping quite current on the updates.
I was cleaning up my system and running some spyware tools 0 Spybot, Adaware and had been trying to resolve some network issues.
After I had finished I tried to start IE and could not get a window opened up. I went thru a number of steps to resolve the problem including editing the registry per the MS troubleshooting information with no luck. Of course you can't just remove and reinstall the software and I was unable to find a hammer big enough to forcibly delete the code and reinstall.
When I did try to reinstall I received a message stating the code being installed was older than the code already installed and the install halted. Downloading SP1 didn't work and I am reluctant to reinstall from my CD unless all else fails. I have rebuilt my system once already in the last 6 months.
It finally twigged that IE was still working when I went to the windows update page from the control panel. I then tried to open up explorer using the Run As option on in the context menu. Two surprises... 1 - there is still an administrator user defined on my system ( I thought I had removed it) and two, when I switch to those "credentials" IE runs along merrily. It would seem to be a privelge issue but I can't seem to sort it out.