Windows 7: group policy on desktop

I went into local group policy on a particular workstation, I need to disable all access to removable device (e.g. usb or cd) on this computer.



under Computer Configuration -> Administrative Templates -> System -> Removable Storage Access, I enabled "All Removable Storage classes: Deny all access", it disabled the USB and CD drive access just fine. I even changed back the setting to verify, it worked fine too.

Couple days later, I need to temporary enable USB stick access on this computer, so I went into the same area, I changed the setting back to "Not Configured", exit and reboot the computer.

once rebooted, I log back in as local administrator, and try to access the data on the USB, it pop up says "Location is not available, X:\ is not accessible. Access is denied."

This is the only place I have changed, but I don't know why the USB doesn't work now even I put the setting back. has anybody come across this issue?

BTW, this is on a Windows 7 Professional x64 machine, brand new installation within a few days.