The windows update icon has been popping up at least twice every hour and stays there for 15 minutes or more. When I drag my mouse over it it says "0% of updates downloaded" always. The updates are not downloading. I have tried downloading the updates through the control panel but that too has been of no avail. What can I do?

Right click your My Computer icon and choose Properties. Click Windows updates & then click Change settings. See aatachments

Do you have any 3rd party firewalls installed such as zone alarm? Is windows firewall enabled?