Everybody sounds like they're on the right track - if I might add something it would be to boot to a C: prompt, change to the windows folder, type "copy regedit.exe regedit.com" without the quotes...
This will allow you to run regedit when you reboot into safe mode. When you get to safe mode, click start run and type in "regedit.com" without the quotes. This will bring up the registry editor where you need to navigate to the key...
HKEY_LOCAL_MACHINE\Software\Classes\exefile\shell\open\command
It's quite a ways down the list but when you get there modify the contents of that key to be exactly...
""%1" %*" with the quotes this time...
Close the regedit, reboot and you should be OK...now gimme my points!