I’ve gotten this in the past with other PCs, but have been able to fix it by deleting my connection in Network Manager and recreating it. I’m using DHCP. This is OpenSUSE 11.3 on a HP Mini-110 Netbook.
Here’s the weird part, before anyone starts sending me to resolv.conf or asking for “lspci” stuff. 
When I’m in a terminal on this netbook, I can enter “host google.com” and it works. I can enter, “host download.opensuse.org” and it works fine. I get an IP address. If I manually enter the IP address in Firefox, I go to the site. But if I enter “www.google.com” in Firefox, it very quickly responds with, “Firefox can’t find the server at google.com.”
“Browse Offline” isn’t checked. (Think about it: if it was, I couldn’t enter the IP address and go to a site, anyway.)
Any ideas? This is a brand new install of OS 11.3, Firefox 3.6.6. But one other interesting thing: the software updater reported that common “curl” error, saying that IT couldn’t resolve the addresses, either.