When clicking on Firefox, it says server not found, if I click on IE it says not connected to network. We just replaced the AT&T modem because last one fried. If I manually turn off computer at tower and reboot it will usually work but not for long. The wifi works fine with our hand held devices so I know AT&T won't help. No issues with previous modem, I didn't change anything with the connections or the computer itself. Any ideas on how to resolve or troubleshoot this? Running windows 7 on a hp