Just found this. No real help, but you are not alone.
http://groups.google.com/groups?q=Ca...ngxa12&rnum=11
I attempt to run the new hardware wizard I am
getting an error message that says:
"Cannot run two device installations. You can only
insall one device at a time. Another device install is
underway. When it is finished you can try this wizard
again".
I am not trying to perform 2 installations simultaneously
and rebooting etc doesn't clear the problem. I have
added hardware before with no trouble and I can only
think this error has something to do with the Sysprep or
Factory Preinstallation utilities BECAUSE when I got my
new PC (with XP installed) the Factory
preinstallation/Sysprep screens would come up every time
I booted the computer. Although the PC worked fine after
I closed this (and things like hardware installation
worked fine) it was annoying and added ages to the start
up process. I couldn't contact the computer supplier so
in the end I simply checked the "Do Not Flag" box in
Sysprep (or Factory Pre..., not sure which) and they
stopped coming up. Great, except that I now have
problems with hardware installation. Could the 2 be
connected? I don't know how (or want to) turn the
Sysprep thing back on. Any advice gratefully received.