FIXED!
I created a new user in cmd prompt:
net user desiredusername desiredpassword /add
than if you want to add that username to the admin group
net localgroup administrators desiredusername /add
Restarted and logged in as newly created user and then typed RUN in start menu search, clicked on run, then typed sfc /scannow hit enter (with my windows 7 sp1 64 bit disk in the drive) and I can now open .exe's, run malwarebytes immediately and good luck.
Just thought I should put an answer on this thread so many keep telling us to download default_exe.reg to fix the registry which seldom fixes the problem.
Geek on a Scooter Fixin' Your Computer
To FIX this win 7 .exe problem:
Create new user in cmd:
net user desiredusername desiredpassword /add
than if you want to add that username to the admin group
net localgroup administrators desiredusername /add
Restart then login to new user.
Run sfc /scannow in the run box
Install Malwarebytes do your updates for malwarebytes full scan immediately. Then install a different virus scanner and do the most extreme deep/full scan possible.
Have a good one,
Geek on a Scooter Fixin' your Computer