Problems with LAN

[Lioness_TAW]

Hi guys,

Hope maybe some of you can help. We have just recently acquired a second PC and have set up a LAN. Everything is working fine apart from one thing. When both PCs are connected to the internet, the master computer constantly alt-tabs. For example, when my husband plays BHD on his computer he gets returned to the desktop every few minutes which can get pretty annoying. The main computer is connected to an ADSL modem.
The other computer is connected with a LAN cable (regular one) to the main computer. (No router.)

So basically it is the most simple network system you can get. We used the Windows network wizard on both systems to get this working. Because we had a firewall of windows on the master, the slave couldnt make connection with the internet.
We turned the Firewall off and now the slave can be used on the internet too. Both PCs running Windows XP.

Any advice would be greatly appreciated.
Thanks,

Lioness_TAW