Manually delete your client.dll and server.dll in your /bin directory and then reinstall 1.06. The files could have been set as in use or read-only when you tried to update, or you grabbed the update from esports.no who actually had 1.05 and not 1.06. Make sure the installer says "1.06" in the title when you run it.
I think I found it out, the second download link offers a 147MB download, whereas the others offer a 157MB one.