Me and my brother want to play Red Alert 2 together but....?

He installed the game (the real, original version, we still have the original key) and we played 2 games online. Later, we wanted to play again but when the game started up, and right before the loading screen and the Westwood company animation appeared, the game had an "internal error and couldn't continue normally". He has windows 7, on an HP pavilion dv6353us, which he got 3-4 years ago. We tried running it as an administrator, tried backwards-compatibility, but both don't do anything. Can somebody help me with this weird error????