Let me add to those experiencing problems with Norton 2009 obliterating access to your shared networked computers under My Network Places (Windows XP). After installation, using the Norton 2009 Antivirus software, all of my networked computers running Norton AV no longer appear under "My Network Places." My home has four wireless laptops plus two desktops running NAV and upon installation, they all disappear from the shared computer list, no matter whether the XP firewall is on or off, regardless of whether they are listed in the NAV Network Map, etc. Only machines not running NAV (or running Linux) will still appear in the list.
However, I can still usually access the machines if I manually type them in as such:
...and so on.
Normally this would just be a nuisance and I'd create some sort of shortcut or other way around this, but my file indexing utilities that index the files on my shared network, so I can rapidly find files on different machines around the house no longer can index anything but files on the host machine. This means that because Norton is blocking the machines from being normally visible, the index utilities I use assume those machines aren't there at all.
If I completely uninstall Norton, the machines can become visible again. Once installed, the machines always disappear.
Access to the machines using the manual method is also not assured as access frequently gets cut off.
I am using the very latest Norton AV version available, run no other anti-virus software, have no special networking software installed, and have tried running with both the XP firewall on and off to no avail.
This is a major nuisance.