Twilight Zone

Seriously.. this is very strange, ive never heard of that happening.
Were you connected to an ONLINE H2H or just through LAN?
Could he look around while in tower (keypad numbers)?
Also, could your friend still switch planes? (if he cant see the hangar clipboard, try the
.plane ## command with ## being a number between 1 and 86.
What kind of system specs do you both have?
Theres a few things i could think of that *might* be causing such a thing - like a bad Cache folder or a vid card issue, or maybe a firewall thing. But thats all just educated guesses.