When trying to run .exe files you may get error messages like: “Access Deny”, “Runtime error” etc..
Corrupt registry settings or some third party product (or even a virus) can change the default configuration for running executable (.exe) files. This often leads to failed operation when you try to run EXE files on your system.
Click on START, and then click RUN (You can search for run in Vista and Server 2008)
In the Run window type “command.com” or “cmd” and press the enter key. (A DOS COMMAND Window will open up.)
Type the following: “cd” and press enter, then type “cd windows” and press enter again (don’t use the quotes.)
Type “regedit.exe” or “regedit.com” and press the enter key.
Navigate to and select: HKEY_CLASSES_ROOTexefileshellopencommand
In the right pane, double-click the (Default) value.
Delete the current value data, and then type: “%1″ %* (Tip: quote-percent-one-quote-space-percent-asterik.)
Finally, close the Regedit Utility window.
Restart your machine, you should now be able to run EXE (.exe) files or programs.