You should remove the -dxlevel after launching the game with it once. tf2 stays the same dxlevel after removing it. Always having it in launch options can cause issues with tabbing in and out.
Don't know if that might have something to do with your issue but it's worth a try and should always be done regardless of MM issues or not
Also like Biscuits said, try 95. It's considered the most stable version of dx9 for tf2