So, lately I've been having some problems with iTunes and Windows Live Messenger. iTunes refuses to update my podcasts, it says that the network connection timed out, when I try to update it says "The iTunes update server could not be contacted.". Whenever I try and run WLM it won't log in, I get error code 800488eb. I'm running vista home premium 32 bit and have avast installed. Anyone have any ideas on how to fix this?

Did iTunes work before behind this router or did you get a new router? On my router someone opened up port 3689 TCP/UDP for iTunes, I'm not sure if it's something you specify or if this is global across iTunes as I have never used the software, but it could be worth looking in to. It seems to be global.
This is also what http://portforward.com/english/routers/port_forwarding/Linksys/BEFW11S4v1.50.10/iTunes.htm.

Also check to see if Windows Firewall is doing what its supposed to do.

It's worked on this router for as long as I've had it up until about 5 or 6 days ago.
EDIT: I've port forwarded 3689 but it's not done anything, I've also tried turning windows firewall off and I can't update anything so I don't think it's that. Anyone got any more ideas?

Do you have any other computers behind this router that you can try iTunes on?

[To clarify, no, I don't have any other ideas, it's troubleshooting time ]

Yeah, I'll just go downstairs and use my sister's laptop, though I'm pretty sure it runs windows live messenger fine.
EDIT: It also runs iTunes fine as well, it's a problem with my laptop.
EDIT II: So it seems a system restore going back to May 31st hasn't helped either.