USB memory stick suddenly not working after using a friend..

Archived from groups: microsoft.public.windowsxp.help_and_support (More info?)

I have a Lexarmedia Jumpdrive 256 MB. I have used it as a backup for my
school work and to work on it when I am not at my home computer.

I have had no problems with going back and forth between home and school
computers, but the other day I used it on my friends laptop, saved my work
and pulled out the stick. When I got home, I plugged it into my home
computer, and (I have XP) a window popped up at the bottom saying the USB
device had been detected, and then a brief window opened showing "scanning"
of one of the folders I had saved on the stick, but then another window
popped up saying please insert disk into drive e. (where the stick was
already plugged in). When I go to My Computer, it shows up as a removable
storage device in my e drive, but when I double click to open the drive, it
still doesn't open.

I went back to my friend's laptop, plugged in the jumpdrive, and voila!
everything was there. So for the time being, I have copied all the contents
of my jumpdrive to a CD.

But what is the underlying issue here? Why can I now only view it on her
computer? I do know that she has not updated her computer with XP Service
Pack 2. Is there some kind of incompatibility when using USB ports and
switching between computers that do and do not have SP2? If so, how can I
remedy this?