I've seen lots of TIDs relating to this but on XPsp2 I'll notice
various p.c.'s map drives in the morning just fine and then lose it
somehow during the day. I have the right clic and log in again and it
just shows "Authenticating SERVER NAME" for each drive letter. I've
turned off the BadNameCache settings as well.

What I found just today was that if I just remote everything from the
TREE, everything from the CONTEXT and just use the IP address and then
click ther SERVERS button to the right, I know see the names of the
server. Click the appropriate one which replaces the IP address and
the drive mappings are back?

How and why?