My issue my not be all related to the firewall.. I remmeber at the time I was trying to render a large resolution screen 3000x2250 and Vue ran out of memory.. Oddly enough even after error and reloading the scene in Vue, it still had the memory allocated. It just seem to run fine after turning off the XP Firewall. System is 3.2Ghz P4 with 1Gig of ram with 6800GT card. Before SP2 it ran fined with same configuration.