StarDestroyer.Net BBS

I was wondering if anyone here can tell me where i'm going wrong. I currently access the net via a LAN. But every so often, the LAN dies and i lose my Net connection on my bedroom computer. When i look up the Network it tells my i have "limited net connectivity" and for somereason the IP address on the computer is blank. Simply going down to the master computer and re-running the Network Set-up Wizard sorts out the problem but i would like to get rid of the problem instead of dealing with the consequences every 2 weeks.

Both my PC's run Windows XP and the cables are all well connected.