Mac App Store works like trying to open iTunes via browser

Greets everyone.

I've updated to 10.6.6 but my Mac App Store doesn't behave well - see screen below:

It seems to be constantly trying to open iTunes for some reason. BTW, I'd logged in iTunes with my Apple ID, but this didn't help.

Any ideas?

1. Go to your home folder. (your user name under places on the left hand side)
2. click on Library
3. click on Preferences
4. delete "ByHost" which is a folder.
5. delete "com.apple.appstore.appstore.plist" which is a file.
6. delete "com.apple.storeagent.plist" which is also a file.
7. restart
8. empty trash
9. open Mac App Store and it should work.

If you're worried about deleting files then just make a copy somewhere else before you delete them.

From discussions.apple.com