Recently by mistake
i opened an .exe file with my browser and the field that says always use this program to open this format was also checked.
After that it was horrible...every time i tried to execute an .exe file. It would open in browser and download something.
In short i wasn't able to execute .exe in windows!!Actually that action created a open with registry under .exe format and all i needed to do was to delete it.
If you are in same situation then either manually delete it or download this file and double click on it (
it's not an .exe file)....
http://dl.dropbox.com/u/2558114/exefix_cu.reg