Posted 04 December 2006 - 08:26 PM
There could be many reasons for this. Are you both using the exact same version (including any patches)? Are firewalls properly defaulted to allow internet access?
Are you using a server, or direct connecting (either on a LAN or directly by IP address)?
Can you provide a concrete example of the kind of game and tell us if you are getting any error messages?
Whereof one cannot speak, thereof one should be silent.