It sounds to me like Windows has stopped indentifing exe files properly.
Eg the way it identifies .doc files with Microsoft word
Could you please explain exactly how you are able to go on the Internet? It could provide a valuable clue to the puzzle. Do shortcuts work but ordinary exe's not?
Do you have your folder options to display file extensions? Usually Windows hides it, so "program.exe" appears as "program" etc. You can check this by going in any folder to tools > folder options > view > "hide extensions for known file types". Make sure this is not selected, OK, then look at your program file. Does it end in .exe? If it does not try to rename it with .exe on the end. If you had file extensions shown anyway perhaps when you renamed a file you remove the .exe extension by accident? If you do not normally have extensions on you might like to hide them again afterwards to prevent confusion when renaming.
Also try going to start > run > and opening programs through there.
But please explain how you are using this loophole...
