I'm not even 100% sure it's DNS, but here's what happens.
After a certain amount of web use, the system stops serving up sites. It appears related to the amount of browser use rather than a specific time.
It works great, no flakiness, no problems, and then, it'll stop on any attempt to look up a website. (Firefox says "Waiting for...")
A system reboot will always work to get it going again, then, eventually, it'll stop.
I've tried commands such as "ipconfig /flushdns", "netsh winsock reset" and "netsh int ip reset" to no avail, though the information I've found on the latter two commands say they don't work until after a reboot. Of course, a reboot fixes the problem anyway, though it will eventually show up again.
It doesn't appear to be browser related. I actually thought this was a Chrome problem, but switched to Firefox and the same thing happens.
Windows XP SP3 on a Dell Dimension computer (can't remember the number, but it's a few years old)
Firefox 23.0.1 (and the latest Chrome, have not tried IE)(cache has been cleaned repeatedly on both browsers, and I even reinstalled Chrome with no luck)
WiFi is 802.11g - router is an open Linksys in the same building, adapter is a Belkin USB adapter on the PC end. The same adapter was used elsewhere without this problem
(And yes, I know the router should be set to be encrypted, but it's not mine - it comes with this place, and the owner won't set WPA, etc., we've already had this conversation.)
There are other wireless networks, about 6 or 7 of them, in the neighborhood, but I suspect if it was an interference issue, it wouldn't work so flawlessly until it stops.
I'm getting sick of having to reboot the computer each time I have an extended browsing session.