Hello, Ahmed , welcome to the gmc.
First of all , this is not the right forum , try next time posting in the Novice Q&A forum.
-Did you try to play any network games (that are not made by GM) on these computer?
-Did you check if the fire wall is blocking your game ?
-Did you inter the right IP ?
Try to re check and reply , but be sure it's not neither a game maker problem nor a windows 7 problem because i have windows 7 and i had network on two computers , however , the GM netwrok example works perfectly !
-mmm I'll try tomorrow because I'm talking about my university computers.
- about the ip I entered a blank (empty string), as I know for local network.
- and I'll check the permissions that I have on my account at the university.
thank you mr.Ahmed