Try plugging into another port of the router. Then I would try another browser, ie Mozilla, to see if the problem abates.
I have two comps amd 1300 and p4 1600 that connect through router through vovange modem both will connect when connected directly to vonage modem but only amd will through netgear router but p4 will not except for yahoo mesinger but ie will not. One that does not work has a realtek rtl8139 network card but one that works has a Winbond w89c940 network card.
Both are running xp pro with sp 2 installed