Here's my setup: Gateway (I forget the model #), running Intel Pentium 4 at 2.6 GHz, 256 Mb RAM, Windows XP Home SP2.
I have the exact same symptoms - only about 10 mins of connection time before the browser stops finding pages.
I was running Kaspersky AV 7.0, thought that was the problem and uninstalled it, but symptoms remain. Like you, I have contacted my ISP with no resolution.
e-mail (Outlook express) works OK, it's just the browsers that stop. Pings to various sites return ok , with no dropped packets.
ipconfig /flushdns also did not resolve the problem. Now I'm going to send this before I have to reboot!
Mod Edit: Split from "Browser Connection Timing Out"~ TMacK
Edited by TMacK, 07 November 2007 - 12:21 AM.