I have just rebooted and at some point following the reboot that doesn't seem related to anything that I am doing (for ex. I could be reading an email; in the middle of my reading the Windows Installer message : Install server not responding, appears. ) If I hit Cancell, I lose my mouse.
Although I have had issues with Windows Installer for a long time, I have never had this problem. This did occur after I have just cleaned and defragged my discs.
What's the exact message, and what is in the title of the window that shows the error? Sometims it will say the program name that's trying to execute when the error comes up.
And when you say you cleaned your disks, what did you do? I'm guessing you did not put them through the rinse cycle in your dishwasher, did you manually delete stuff, use some type of auto registry cleaner, etc...? A program should have an "undo" feature, see if you can use that to fix things.