Baffling situation

[Norm]

If I boot tp level 3 and do some command line admin stuff then switch to 
a user account and continue to open  a gui interface my thumb drive is 
not permitted to mount. At the gui level if I log out as a user  and log 
in as root the drive loads, I can then switch back to a user account and 
the drive is loaded, my other choice is to go from boot through run 
level 3 and open the gui as a user and the drive is mounted.  I have not 
checked but assume that I could also go straight to run level 5 and open 
as a user and the drive would be mounted.
What I do as root at run level 3 does not seem to be the problem, it 
seems that the simple logging in as root  is the problem.  The choices 
to work around this are easy enough but I would like to understand why 
the issue occurs,  Have others run across a similar situation?
Norm