BleepingComputer.com: internet freezes

Can someone direct me please. I have a Vista laptop SP 1 with Avast and Zone Alarm firewall running. This is a fairly new laptop and most of the time, surfing is not a problem, but sometimes it seems to freeze. I can get out of it okay and the rest of the computer is running ok, but if i try to log back on to the internet, it doesnt have a connection. If i restart, its fine and fires back up ok.
The thing is, i have an XP PC desktop which runs fine at the same time.
Should i be looking at something in particular or is it something to do with my internet provider - sky - but if thats the case, it should happen on my main pc right?

I have an internet cleaner installed so when the last page of ie closes, it cleans the temp files, cookies etc;