No access to USB pen stick in XP

i look after a well established Lan, Win2K 35 stations fully “patched and s-packed”. BUT now i have setup a brand new Laptop, Win XP, SP2 etc. It is joined to our Lan, HERE IS THE PROBLEM, the user can no longer use his usb memory stick “when logged in to his own profile”, I’m sure this IS a rights issue as when i log in as Administrator it works fine. PLEASE understand this, he can use the stick on a Win2K station but not on the new laptop. giving admin rights to local user doesnt help, XP recognizes new usb device and it list it in the “Unplug/Eject devices” etc but the drive icon does not appear and is not accessible, what can be stopping laptop users from using a usb pen stick. Thanks JohnM
ps, this is happening on all new laptops not just one isolated one.