Ferman wrote:

NOTE: OP's use of two newlines to separate sentences (making
indistinguishable any paragraphs) were replaced with a single space.

I have a Win XP pro PC and a Win 7 Pro PC. Sometimes when using my
SanDisk Ultra USB3 128G flash drive it says it is write protected. I
do not do this ! I cannot figure out how to un-writeprotect it in the
Win XP pro PC. THERE IS NOT MECHANICAL SWITCH on the flash! But if I
put it in the Win 7 Pro PC and do a quick TOOLS/ERROR-CHECKING check
it will take the write protect off and I can then again use it in Win
XP Pro. How do I do this in Win XP Pro without have to lug my Win 7
Pro desktop around with me when I travel ? I have other flash drives
and this never happens on them.

See if the following works:
https://www.isumsoft.com/computer/re...gedit-exe.html

Also try reformatting the USB drive. If the drive is inaccessible
(reporting it is write protected), you will need to use a 3rd party
formatting tool (e.g., Easeus Partition Master Free).

I'm not sure how permissions could be a problem even when using NTFS.
Permisions are enforced by the instance of Windows under which they were
defined, so they are unknown to another instance of Windows. If you
have the USB drive formatted using NTFS, reformat using FAT32 which has
no attributes in its file records regarding permissions.