USB Drive

Has anyone come accross this. I can't access my USB drive(memory stick) using explorer and it doesn't appear in my computer. However the drive letter is J: I can create a shortcut to it but an error message comes up saying "This operation has being cancelled due to restrictions in effect on this computer. Please contact you administrator" when trying to access it. If I open a D.O.S. window I can access it no problem.
I've tried copying the USB drivers from "i386" to the "drivers" directory and the "inf" directory but still it will not work.
Anyones help with this would be gratefully appreciated as my next step is to format and re install.
Cheers Jasbbo.