XP holds connection after disconnect

I have a bit of a strange one going on. My computer connects to the internet no problem (dialup or asdl) but when you disconnect it appears to keep the connection. In task manager it lists the connection but with 0K connection speed. If you try to connect a second time it connects ok but you cannot access any webpages (DNS doesnt seem to work).

The only program I can think that might be preventing a reconnect is Zone Alarm (free ed) as a couple of years ago, when I wasn't using ZA, I didn't have this problem on XP. The same happens on another PC at home with XP and Zone Alarm.

Any suggestions?

Sounds more like a trojan activity to me... www.emsisoft.com have a freeware trojan killer and checker. If you want to confirm it's a ZA problem, completely uninstall ZA and see if it still does it.... no disabling is not good enough - there are processes which continue to run even when "off"

I've run the scanner you suggested and there's nothing been found. I also use Spywareblaster, Spybot, AdAware and MS AntiSpyware and they haven't found anything either. PC-Cillin hasn't had anything for a while so I can only assume it's ZA. I'll try whipping it off sometime.