If Win7 can't open any exe file, and u get a fault message of some kind, and when restart u can't get in.
Do u got ZoneAlarm installed?
If so Uninstall ZoneAlarm and the problem should go away.
To uninstall ZoneAlarm u need to start in Fail safe mode no network.
To get to Fail safe mode press F8 key after BIOS before Win7 trying to start.
Now you going to get a lot of choices but choose Fail safe mode no network (or similar).
When in Fail Safe Mode go to Control Panel and then Programs and Features.
Now uninstall ZoneAlarm and let it restart the PC when its done.
If the problem persist u got some sort of a AV.EXE virus. Google that and find a solution.
Hope that it helped /Freddy