Is your xp set for 32 bit. And the win 7 to 64 bit. ???
For i have had the same problem. Never could get a why out of it.
Except this. One will set the other as write protect. Well, my blue
tooth stereo turns itself on but that is not possible. Something in
the room sends radio signal when I did not touch nothing to do so with.
I can only believe it is a microsoft. They are such ass holes.
write protect is not possible in a flash drive, but on a chip yes. I
have a multi chip reader. If its not san disk, its another kind, but
they all do it. CAUTION, once it erased all of itself all by itself.
And that, was a real ****er. For I did not not back up what I had on
it. All software has a way to program it in windows 7 before you set it
up on its machine. Its under the right click properties tab. Go in
download folder, and try it on a downloaded software that you have
downloaded. Once you open the properties window, click the
compatibility tab. Then read all the choices of op systems you have
to run it under. In the drop down menu. Now you get my drift of why
it is happening. It may be reset to a 32 bit verses the 64 bit. And
that, will certainly make it screw up.

On 3/12/2018 2:18 PM, Ferman scribbled:
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 !

Why and how does this happen ?

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.