Windows XP is not opening any exe programs

Recently I installed Windows XP SP2 in my laptop. Initially is worked
fine. But now is in problem. I am not able to open any programs through
desktop shortcut icons or through start-->Programs menu option. But I
am able to open the file through command prompt by moving to the
installed directory. For example,If I want to open IE, I will move to
installed directory(C:\Program Files\Internet Explorer), right click
the folder, selecting prompt and by specifying the file
name(iexplore.exe).

If I double click the file(iexplorer.exe) is also not opening.
Similaly,I am not able to open command prompt through run command.Some
of the links under Control panel(Add or Remove Programs,Date and
Time,Display,Keyboard,mouse) are also not working.

Any quick help will be appreciated,


Thanks,
Senthil