Try uninstalling Darkcorp. I believe that is causing the issue. Just use a backup channel for your backups.
I have the same problem. I'm uninstalling Darkcorp as we speak.
EDIT: NSMBW works after uninstalling Darkcorp.
After the previous insanely stupid mistakes nintendo has made lately, I would normally have a pretty smartass comment. But I'm gonna make a very valid point here. Does everyone remember when Nintendo sold the rights of Banjo & Kazooie to Microsoft? Guess what, Microsoft managed to give that game...