Wireless 2350 Broadband Router Has Connectivity Problem

Hi,

I use AT&T's High Speed Internet (via phone) and Dell Wireless 2350 Broadband Router.  I set my laptop as the main one (because my wireless card is damaged) and my roommate's laptop as wireless client.  Sometimes she can surf on the Internet, but she sometimes sees "limited or no connectivity" pops up and cannot connect to the Internet.  I did not set up WEP security settings.  Her default TCP/IP settings were all automatic instead of giving specific IP and DNS, etc. 

I have tried unplugging cable and wireless router, wait for over 15 minutes, then power on cable, one minute later power on wireless router, and reset her laptop.  Most of the time, she still saw her network icon at bottom right screen had a yellow triangle, in which was a signal ' ! ' (limited or no connectivity)  Only a few times this strategy worked and brought back her the Internet.

Today, I followed Dell’s instruction: log into http://192.168.2.1/index.asp, and chose DEVICE STATUS.  I found all connections between LAN, Wireless, and Internet, and router were all ok.  I changed my roommate’s TCP/IP settings: from AUTOMATIC to IP: 192.168.2.100; DNS:68.94.156.1; Gate IP:69.110.223.254.  These settings were based upon below figured obtained from http://192.168.2.1/index.asp and chose DEVICE STATUS.    I also set up a password at WIRELESS SECURITY under BASIC SETTINGS, and key in the same password in my friend’s laptop.  Her laptop showed already connected to the Internet, but we failed to open any webpage via the Internet Explorer.  So, actually, she didn’t have access to the Internet.   

Sometimes, she also saw “IP address was incorrect.”  Can anyone help to solve these problems?  Thank you very much.

ps. All my TCP/IP settings are AUTOMATIC, either. 

Joseph