I've a strange problem. I've desktop with Windows 7 Ultimate (with admin access) and an office laptop Windows 7 Proffessional with limited account access. The USB drives are getting readonly when plugging into the Desktop.
1. I plugged the drive to laptop, I can copy files to the drive, fine.
2. Then I plugged it to the desktop, I'm able to copy files to the drive, good.
3. Then I plugged the drive back to the laptop, I can see the files but not able to copy/rename files on the drive. It show an "Access Denied" error message.
I checked with my USB flash drive as well as a external hard drive. Both behaves in the same way.
Check if Drive/Data Encryption is on in Windows on the Desktop.
Control Panel> Bit Locker Drive Encryption > All Drives.... set to off.
Especially the USB Drive when plugged in and the External HDD when plugged in need to be set to OFF.
Do the same when you plug them into the Laptop and set it all to off.