If your applications are no longer launching, it’s probably the result of a virus that has recently been removed, breaking the file association between programs and .exe files. The .exe not opening requires a registry repair to correct it. Aside from the program not launching, a typical symptom of this problem will be shortcuts changing on your Desktop with the .LNK extension. As you know, your machine would be rendered almost useless in this condition.
While it’s not unusual for a file extension to lose its application association, it IS unusual for a .exe file to lose its ability to launch a program.
If you know this was caused by the recent removal of a virus, you need to try and perform backups before you proceed, as you will be running scripts that attempt to fix the registry–which is always risky.
Backup The Registry
The easiest way to backup the registry is to create a system restore point. Creating a system restore point takes a snapshot of your computer’s registry that you can later restore if there is a critical issue. To create a restore point, go to Start>Programs>Accessories>System Tools>System Restore. Choose the option to create a new restore point.
Once the registry is backed up, you should try backing up any important documents, pictures,movies and any other data you do not want to lose. While it’s not likely the registry fix will damage your computer, it’s always a possibility.
When you’re ready to proceed, there is a very detailed explanation of this problem on another site for the .exe files not opening problem. It has fixes for both XP and Vista. Once you run their fix, restart your computer. The registry should now be repaired and your .exe files should launch their programs as intended. Get the .exe fix here.