Upnp help

Hi folks, I'm new here and desperately seeking suggestions.

A few weeks ago I fiddled with port-forwarding on my router in order to get faster download speeds in my bit-torrent client (Vuze). Since then, I've been experiencing problems : my POP email and Gmail accounts are often not accessible. The only way to get my messages is to shut down, unplug router and modem, re-plug and re-boot. This works for awhile, then the same problem occurs. Regular Internet connection works ok.

Someone advised me to clear the port-forwarding and enable UPnP, which I did (in Vuze and my router), but this didn't help.

I should add that we've got a second computer in the house, and the situation seems to improve if that computer is off, or is turned on AFTER mine. Basically, one computer or the other suffers in terms of connection speed and email ability.

I see this is a PC-based forum, and I'm on a Mac, but I'm hoping you can help anyway.

Specifics:
2 Intel Macs, OSX 10.4.11 using built-in ethernet
Netgear RP614v3 Router
Scientific Atlanta cable modem EPC2505
Vuze TCP/UDP port : 63128
Firewall is off
Entourage Office X

Please, any ideas? It's driving me nuts and costing me in time and energy.
Thanks.