Network drive mapping is "lost"

I run a home network with 2 XP machines and a d-link network drive. I added a
Vista machine. Of course, as feared and expected (I am really annoyed with
Vista's utter lack of reliability even on simple tasks) mapping a network
drive doe snot work as it should. I am able to map my network drive on Vista.
I can access the drive, but at some point, without any indication as to what
the tirgger is, the drive is no longer recognized, nor can it be connected
again. I have to run the setup routine provided on the d-link cd. In
instances where the drive stays connected throughout a session, the drive
vanishes once th emachine is rebooted, comes back from hibernation or
suspended mode. I checked the "reconnect on start-up" box, yet this doe snot
change anything.

I have used this network setup for a long time and never had any such issue
with the XP machines. I would really appreciate if a Microsoft employee would
respond with a simple description to resolve this issue. I am not a hardcore
techie.

Thanks