Disable Data Execution Prevention (DEP)

Going through this:

Right-click "My Computer" --> Select "Properties" --> Select "Advanced system settings" --> On the tab "Advanced", the first box "Performance", select "Settings..." --> Go to the third tab "Date Execution Prevention...

Damned! Why there is no such an option to turn off DEP for all programs?

Solution (partial) finally found:

http://vistasupport.mvps.org/disable_data_execution_prevention.htm

Checking Corrupted System File

You can run

sfc/scannow

to scan system files.

If the Explorer.exe application itself is damaged, you can copy an explorer.exe file to your computer from another computer. Please first open your Task Manager, end the process explorer.exe, and then store the new explorer.exe file into the directory WINNT (Windows 2000) or WINDOWS (Windows XP / Vista) in system disk.