XP Workstations Lose Connectivity to Server 2003 Share

Here is my dilemma.  I have researched this issue by looking at several posts and made changes based on those posts with no resolution.

There are 4 workstations, 3 XP SP2 and 1 Server 2003, that have an application loaded locally however all the required reports are located a HP Proliant running Windows Server 2003.  This application requires a share called RescueNet, which is located on the HP Server and the directory is c:\program files\pinpoing techonologies\.  For whatever reason the software manufacturer did this and not use a web-based reporting module is completely beyond me however this is the issue.

For some reason, these 4 workstations that rely on the RescueNet share on the HP server, seem to lose connectivity to this server several times throughout the day.  The only resolution up to this moment in time is to reboot the HP server.  Once it comes up, the issue goes away.  

Here is what I have done to this point.  I had HP come out to replace the system board.  That didn't fix the problem.  Modified the registry properties for the timeout.  This is the registry setting I changed on the HP server.  HKLM\System\CurrentControlSet\Services\Lanmanserver\parameters to -1, which disables the setting.

The firmware is all updated with the most recent versions.  The NIC's are not teamed and only one is plugged in to the network.  There is no setting to disable timeouts on the NIC as I have read in previous posts.

That's about all I can think of at this point.

Any help would be greatly appreciated at this point.

Thanks.

Peter