OK, I tried adding the AVI section like you posted but it did not seem to change anything. I used to have the overall resolution and Interface resolution at 1024x768 but my Radeon x1950 would sometimes lose the connection to the monitor when exiting the mission. I thought keeping the resolution the same would help the problem (which it does), but I just can't see the radio menu when in a mission. Very weird.
Thanks for your help so far.