Windows XP Disconnected Network Drive problem - Drives los..

Hello,

Probably anyone who read the title already knows what the problem is.
But for those who dont, here is the rundown.

On our network, we run a logon script every time a user logs in to the
domain. This script should map all the network drives that an employee
will use for their shift. So every 8 hours, a user logs out and a new
user should log back on, which in theory should rerun the script and
remap all the drives.

The problem though is that after 3 or 4 days any user on that computer
will lose all of their mappings, and a logout/login will not fix it.
ONLY restarting the computer will bring back those lost maps. The
drives will appear in My Computer as "Disconnected Network Drive", and
cannot be deleted through right click>disconnect or net use * /del
command (both give a message that the drive is not in use). We have
several drives that this error appears on. One of them I can click on
and still view all contents, regardless of the status indicated. On a
couple others, I click on them and those will also take me to that
other network drive that says disconnected.

To clear things up, these are very high priority machines that run
24/7 and shouldnt be shut down for any reason (they do 911
dispatching). One user logs out and another should log right back in
to continue the job, so I want to avoid having to restart every few
days. You cant really trust users to do it on their own anyway.

I have tried this solution from microsoft with no luck:
http://support.microsoft.com/kb/932463
I am aware that one potential cause is Symantec AV, which is what we
are running. I MAY try uninstalling and seeing if it fixes it. These
users shouldnt have internet access anyway.
I have also tried some manual logon scripts that delete mappings with
net use and then redo them every time a user logs in. No luck there
either, and the domain logon script should do that for me anyway.

The BIG REASON that I need this resolved because the mission critical
software that we use does not recognize UNC paths, and therefore
needs a particular drive letter to send output to.

After the long-winded description I feel like I'm beating a dead
horse. I hope I hit all the details, and I know I'm not the only one
who has seen this. Any suggestions?

Thank you,
Bret