I think Synack is on the right track here. I have seen it in our network as well.
To start off you can clean the registry of those mappings (just start regedt32 and import the users .DAt or .MAN file into a hive, change it, and save again) . However it could be a profile sync problem as well. (the pc grabs an "old" local profile if it can't grab the roaming one).
bio...