when i try and play someone it says there is an error and goes back to the main menu, but my internet connection is perfect!

if the error is during the synchronization between your opponent and you, then the error is either your computer cannot join in !

either your opponent's game is closed or has started !

for the first option... see if you are behind a router or firewall. if not then it may be only bad luck, try again a few times.

if its the second option... then you cannot do anything about it, its all about your opponent and not you !

to be more precise we'll need the complete error message !