Ok, article looks like it\'s all you need. Create the answer file it talks about and run the program. Run it once with Paint set to off, and once again with it set to on. That should uninstall then reinstall it.
Alternatively, you should be able to just extract the mspaint.exe program yourself. First, delete the c:winntsystem32dllcachemspaint.exe program. Extract a good copy to c:winntsystem32; then back to c:winntsystem32dllcache. That should work for you.
Usual disclaimers...I haven\'t used the first procedure at all, but I have used the second one. If your PC blows up...don\'t look at me. Blame someone else (OpenFriday is a good guy to blame, it\'s usually his fault anyways).