DiskOnKey problem

We have a manager who has a Dell Dimension XP Pro system and is trying to use a DiskOnKey device in his USB port. He can access the device logged in as administrator, but when he logs into the domain under his name, the device shows in the systemtray, but the DiskOnKey software will not see the device. He is part of the admin group on his PC. DiskOnKey support said that they replicated his problem and got it to work by cold-booting and logging in as the user, but it didn’t work for us. Anyone have any suggestions or have any problems with DiskOnKey devices and XP systems? Can you set permissions on devices in XP?