Have you tried right-clicking on the shortcut to the program, or the .exe, and selecting the "Run As Administrator" option? Do so even if your user is an Admin.
Try right-clicking on the actual Setup.exe and selecting the "Run As Administrator" option? Do so even if your user is an Admin.
Try Safe Mode.
Advanced startup options (including safe mode)
http://windows.microsoft.com/en-US/windows7/Advanced-startup-options-including-safe-mode
How to troubleshoot a problem by performing a clean boot in Windows Vista or in Windows 7
http://support.microsoft.com/default.aspx/kb/929135
Test with another Windows user.
Try System Restore.
How to repair the operating system and how to restore the operating system configuration to an earlier point in time in Windows Vista (or 7)
http://support.microsoft.com/kb/936212/#appliesto
Try running ChkDsk to check your drive for errors. Right-click your Drive icon/ Properties/ Tools/ Error Checking. Try it first by not checking either box (this will run it in a Read-only mode) to see if it flags any hard drive or file problems. If it does, restart it by ticking both boxes, and rerun it to allow it to attempt to fix any found problems.
Uninstall and reinstall the program.