Hi Globaltime,
1. Have you made any recent changes on the computer?
2. Are you able to access programs available on the start menu?
Method 1
Run the fix it available in the below Microsoft article and check if it works.
When you run an .exe file on a Windows Vista-based or Windows 7-based computer, the file may start a different program
http://support.microsoft.com/kb/950505
Method 2
If the above step fails then you will need to restore the file associations for the programs that are opening using Windows media center.
Change which programs Windows uses by default
http://windows.microsoft.com/en-US/windows-vista/Change-which-programs-Windows-uses-by-default
Hope this helps!
Halima S - Microsoft Support.
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