I had my PC running over night and when I checked it in the morning, I found neither IE nor FF were running (maybe I closed FF, that's not important). So I tried to launch them, but neither browser started and FF threw the following error: "XULRunner - Couldn't read application.ini".
I cleaned Windows up and restarted, but it didn't help. I found both apps can run when admin rights are used.
Where the problem can lie? Should I try changing some registry values?