ahem, i am more dumber than i really thought i wuz.

on the pdc [nt4] in user manager, user environment profile screen, home directory > i had specified for some groups;
Connect U: \\server_6\%username%$

i am guessing that kixtart then deleted that but couldnt then remap to that drive immediately again.
i solved the problem by 'Connect Z: \\server_6 etc....'
and that worked.

is this a kixtart/ms bug? or am i just doing the wrong thing to start with. anyhoo, i am much happier now.
thankyou for again reminding me to tidy up the script. i will.