I have 2 snap 4100s I do not use them for user profiles but I have not seen any problem with drive mappings to them...I run alot of scripts and batch installs from them. (I have other problems like poor upload speed and one keeps re-booting at random)

maybe its a network problem.
Do you have the snap set up with a static ip?
do you have a wins server set up?
do you use NT authentication? (not sure if this is availble on the 1000 model)