Regarding the write protect error, I believe its a common symptom for fake USBs. These are ones which say they have large capacity, but the seller placed a much smaller capacity chip. In your case, its possible that the pen drive's REAL capacity is only 256MB! Even the OS is fooled into thinking its a large capacity USB drive.
I saw some Sony branded USB's with a capacity of 32GB a few months ago. They are obviously fake.. but I do wonder how many people fell for them.
Be wary when buying USB's from sites like ebay
