Solaris mapped drive filter woes

Using a legacy FSFD on several Windows XP Pro machines mapped to a drive on
a Solaris machine. Some of the XP machines are seeing the activity on those
drives, others are not.

I used DeviceTree and could not see a difference between the working and
non-working machines. They all are successfully attached to
LanManRedirector.

Any ideas what else to look for? Why would some work and others not?

Thanks.