Fedora :: Can't Connect To Non-HTTP

I'm using the Netopia 2247 router. I'm on Fedora 13, on a Thinkpad T60.

For some reason, ever since I switched my ISP (just last night), I can't connect to any non-HTTP services. I've tried Thunderbird for IMAP, FileZilla for FTP/SFTP, and Empathy for XMPP. Nothing connects. Chromium, Firefox for HTTP: works just fine. I know it seems really far stretched to think that this could be an issue on my end, but: I've checked with the ISP, and they insist that there's no reason this should be happening. They will be coming in tomorrow to take a look at wiring and all that though. I'm able to access my IMAP email via my smartphone's built-in mail client, via my new ISP. This is using a Nokia N82, with default messaging client (just called Messaging). But, who knows, maybe N82's email client actually uses HTTP? (Unfortunately, my only "desktop" computer is T60, and I only have Fedora installed on it; I realize the icon at top right shows Windows, but that's my work desktop, and I definitely can't take that home for testing). I've checked the firewall settings on the router, and put them at the very lowest setting.

Again, I know it seems far fetched that there's something wrong with my system (e.g., I've traveled with my laptop and have never had any problem accessing IMAP or FTP on other connections), but I just want to make sure I've exhausted every possibility. So, if you could entertain the possibility that it's something on my end, what might it be?

Maybe disabling SELinux might help? I'm going to try that when I get back home. Although: I feel like an SELinux dialog would've popped up if that was the problem.