My friend has a fairly new stand-alone (not network or domain) Windows 7 Professional desktop PC with MS Security Essentials as protection. Using a Win7Pro User account which has administrative privileges, when attempting to access any USB flash drive (tried using a selection of flash drives), a "You Do Not Have Permission To Access..." message appears. I have rebooted the computer in Safe Mode and the USB flash drive is accessible from Safe Mode. Using a Win7Pro User account which has administrative privileges, the following occurs... Access (permission) is denied to all USB flash drives on all USB ports linked directly to the PC's motherboard. Access (permission) is denied to all USB flash drives even with manufacturers' drivers. Access (permission) is denied to all USB flash drives (with or without data) from an administrator's command prompt. The Auto play menu works when plugging in USB flash drive. The account is an Administrator account (not Standard). The "Everyone" group has Full Share permissions (there is no Security tab presumably because the USB flash drive is Fat not NTFS). Removing the USB hub does not have any effect on the built-in USB ports. Running DriveCleanup.exe has not corrected the issue with not being able to access the USB flash drive. Non-drive USB functions work in the User account with administrative privileges (but not USB drives). No group policy settings have ever been set, i.e... Everything is set to "Not configured" in... gpedit.msc -> administrative templates -> system -> removable storage access. Everything is "Not configured" in the User section of group policy. Can any throw some light on this issue please? Many thanks in advance.