So im browsing the webs, talking on irc, talking on aim.

Randomly I lose any connectivity to websites. Firefox, IE, and Opera do not work. They all have error messages saying things like "Cannot connect to server"

AIM and IRC stay connected however. Restarting the router doesnt fix it, only rebooting my machine. Im fairly certain the windows firewall wasnt running when this happened.

The only thing I could think is maybe ports are being blocked, or some sort of upload limit is being reached?

Unlikely. If ports were being blocked, A) They'd probably always be blocked, and B) restarting the router would fix it. Also, if it were a cap, it would be set remotely, not on your local machine. So rebooting wouldn't do anything.

Other than that, I've got nothing.

Does your router support QoS? Toggle it if it does and see if the behavior changes.

This happens to me occasionally, too. For me I think it's mostly isolated to my firewall and service provider, but that doesn't really help you out. One other thing I do that sometimes fixes it is "ipconfig /flushdns" in the command prompt. I suppose give that a go next time and see if it helps.

err yeah, flushdns. I didn't notice that typo, thanks bob.

I've had this happen to me as well, although I hadn't heard about the flushdns before

Flushing the DNS should fix it.

This same things happens to me after a few days without a restart, but only in Windows XP. My guess is that it's something to do with XP, but I'm not entirely sure what.

WINDSOCK

I think you mean WINSOCK.

I enabled QoS, so I'll let yo uknow how that goes.

Since new connections aren't getting through, but existing ones remain, I'd wonder about DNS - You should check whether you can navigate to sites using their server's IP address rather than their name.

I've just pinged Google and got 209.85.135.104. Write that down on a sticky note and next time it happens put that in your browser instead of [url]www.google.com[/url]

You might fix it by using OpenDNS. It's a free DNS service, an alternative to your ISP's. You put their DNS server IP in your connection options and that's it.

ipconfig /renew

I think it'll wooork.

Doesn't /renew just get new IP addresses from the DHCP server (for those connections using DHCP)? Which would only fix it if the IP address it was currently using had got screwed up somehow. The fact that IRC and AIM still work suggest that that isn't the case?