Connecting to internet problems

When I log into Windows, and connect to the internet using my Speedtouch modem, I don't seem to get anything. I cannot connect to any websites or programs that use the internet, even though the program that connects me says it is connected.

I haven't changed any settings to create this problem, and I'm sure the modem works as it is ok while I use Ubuntu. This problem only affects Windows. Please can you guys help me fix this problem?

did you use another computer when you posted that then? o.o

could it be that it's your host that's down..?

You happen to install any sort of firewall on your computer recently? I've seen some Windows software firewalls that on maximum protection cause the internet to cease working completely.

I'm using Ubuntu atm, even using the same modem as I do on Windows.

I haven't installed anything at all recently. It was just one day, I came to turn the PC on. Logged in to find the internet wasn't working on Windows

Just a few suggestions:

Spyware?
XP Firewall Advanced Internet connection settings - allow HTTP ?
Internet Explorer set to Work offline?
At command prompt - Can you ping a website i.e. 'ping www.google.com' ?
Tried resetting IE default settings?