I had an Actiontec ADSL router/gateway thingy. It would get locked up anytime I passed lots of traffic across it. I changed it over to bridged mode, and set up an old P3 I had lying around as a Smoothwall firewall/router. It now handles all the PPPoA authentication and everything. And a P3 has TONS of power and overhead to route like crazy.
Nary a problem since I've done so.
You guys should check it out.
www.smoothwall.org -- 50 MB .ISO you can load on a PC with a pair of network cards. Even more powerful than a Cisco PIX.