Perr to peer and Norton Internet Security problems

I know this is a server based newsgroup so maybe someone can just point me
in the right direction if they can't help.

This is a 3 computer peer to peer network with one computer acting as a
server holding the files for InvoMax Shop management software. (Automotive
shop software) All systems have Norton Internet Security running with each
computers IP listed in each others "Trusted" zone.

When the systems are all booted in the morning, none of the computers can
access the mapped drives of the others. The mapped drives show up with a red
x, disconnected state. We must then disable the firewall of Norton, and we
must then click on the disconnect drives, and then they become connected and
all is well.

If after that, we enable Norton, we SOMETIMES may continue to operate. But
SOMETIMES, enabling the firewall shuts down the sharing and we must disable
Norton and click on the drives to reconnect.

Any direction at all would be so much appreciated!

Thank you very much.