open Regedit and navigate to
If there is a WriteProtect key (REG_DWORD) then
1 = Write Protect On
0 = Write Protect Off
Set to 0 and try (may have to reboot in some cases)
1. Go to the disk properties page.
2. Select the 'Hardware' tab.
3. In the 'All disk drives' list, select the name of the external device.
4. Click the 'Properties' button.
5. Select the 'Policies' tab.
6. Under 'Write caching and Safe Removal', select 'Optimize for performance'.