both comps are running windows XP pro, and i've tried deactivating the windows firewall, and no changes.
I've been having strange connection problems on both pc's connected to the internet. I've had a router (D-link DI 704UP) for about a month now, but the problems popped up just recently. Some applications, like steam and some p2p programs do not connect. I can get online just fine, download things and do things as normally but any program that needs to connect on startup seems to say it's behind a firewall. I disconnected the router and went direct to modem, but that fixed nothing. All p2p programs are experiencing same connection problems, on both computers.
any ideas/tips as to what's going on?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic