Cannot run ANY programs!

Today AdWatch notified that something was modifying my registry.
I clicked block, but after restarting my systems all my icons are standard and no programs will run except .msc files.

This means that I cannot access the registry, not even by command prompt.
I cannot run my AV program.
Adaware won't run.
I cannot run any .reg files.
I cannot run system restore.
I cannot run Hijackthis


I've tried various fixes found on the Internet, but because the .reg files won't run they don't work.
It seems like I might be able to run .inf files.
Opera is working still as is Outlook.

I'm on windows XP SP2

I really need some help with this. I don't want to do a reinstall now! It's only been a couple of weeks since I did it last time.

TIA

 

I just realized I can't even run .com files!

 

Sorry for the bump, but this is really killing me!
I'm wondering if its possible to rename .reg files to .ini files
In that case I might be able to restore the file extensions in the registry!

 

Desparate times call for desparate measures.. I say that because what I am offering as a 'solution' has not been tested. All your associations are pooched, so you need to fix the registry - there is one tool that comes to mind The Offline Registry Editor maybe you can edit the registry just enough to get .reg files fixed then repair the rest in windows.