Have RT314 for about 2 years, and lately have these problems occasionally. I believe it is an obvious DNS problem.
While I used to be on @home network, I didn't have any. Since attbi (AT&T) took over, these troubles started. I use DHCP assigned everything, and in order to make the router work in the first place, I had to completely reset it to factory default to get rid of the older @home entries (the unplugging/rebooting didn't solve that, needed full refresh).
Some people recommending to disable DNS client service (default is automatically started) in WinXP and Win2k (since it's caching DNS which attbi seems to be changing frequently; or at least alternating primary-secondary -tertiary ). I let it as it is since don't have these problems too often, but may help to some.
You can try to stop and restart DNS client service as well to see if it would do any good. Win9x don't have such a feature, so they work correctly (reflecting DNS changes instantly)....
I don't think it's Netgear's fault, rather the one of ISP....