OK folks...
I've tried going back to Archos OS..no luck..same situation. So it is not Rockbox OS. I believe it is something that was introduced in SP2 for XP as that's about the time I remember it ceasing to work on XP. To test this theory I will later try installing Windows 2000 and see what happens.
but for now...
I have been able to mount the drive in Linux FC4 no problems and read write files with ease. For those of you that can use/access Linux in the meantime, this seems to be your only recourse. And if nothing else works with XP, this is going to be the only way I access the files on my JBR 20GB from now on.
I am tending to blame MS for now for changing something to do with Mass storage USB devices, though what it is, I don't know. All I know is that it used to work without problem, then one day it stopped and produced the "Do you want to format drive" error that several of us are complaining about.
Will Update later after I try Win2000 pro...till then.