I highly recommend that anyone who purchased Norton Internet Security or a computer that came with it preinstalled, uninstall it immediately and get something else. The firewall that comes with NIS is completely brain-dead, and to date EVERY computer that we have worked on which has NIS installed has had issues where the firewall keeps the user from doing anything network-related.
The idea behind a software firewall is that it keeps the bad guys out of your computer. The problem is that Norton Internet Security seems to take this a step further by keeping you from getting on the Internet or even your local area network! I suppose that the truly draconian network administrator could argue that this is more secure, but the far cheaper and simpler method would be to simply disconnect your Ethernet card from the network.
If you need a firewall, Windows XP comes with one built in, for free, and it works well. There are also plenty of other firewall, anti-virus, and spyware prevention products out there. I’ll list a few for your reference:
Windows XP’s Built In Firewall – Microsoft – Free
Kerio - Sunbelt Software – $20
ZoneAlarm – Zone Labs – $50
Norton Antivirus – Symantec – $40 (yes, this product is okay)
AVG - Grisoft – $39
AVGFree - Grisoft – Free to NON-business users for ONE computer only.
Windows Defender – Microsoft – Free
Spybot Search and Destroy – Free
AdAware Personal – Lavasoft – Free for personal use
SpySweeper – Webroot – $30/year
Alternately, just buy a Mac.