That is certainly one possibility. What kind of USB device is is: Flash memory, a hard drive in an external enclosure, something else? Brand and model would be useful.
The most trivial answer would be that some USB flash drives have a write-protect tab.
Another trivial answer is that your PC may have a policy set not to write to USB devices; can you write to any other USB device?
And the always unpopular: Your drive may be failing.
Awaiting details, unless vvhocare5 hit the nail on the head.
Hi, i am facing the same problem and i am not able to write anything to any of the USB drives however i can read/execute from the drives. The probably means the USB ports are working well and looks like there is some policy on my machine which prevents me from writing anything to the USB drives. Can you please help me with this problem? How can i get my songs copied on my USB drive?