Windows Can't Install MTP Device

Hi

Since I upgraded foolishly to Media Player 11 from 10 my XP Pro PC won't
install and dock with my Creative Zen mp3 player. It says found New Hardware
but just keeps "popping" and cycling and never installs it. Same goes for my
Tomtom Sat Nav - can't install drivers for it. I have researched extensively
and have tried a rollback from 11 to 10 - that doesn't work. I have
unstalled the Media Runtime and all the suggestions on MS site. I can't
reinstall WMP 10 as it fails - presumably WMP 11 is so deeply embedded in
Windows they don't want people to go back. New Hardware Wizard fails to
install it. I am stuck with WMP 11 and no ZEN or Sat Nav connectivity. I
have unstalled all USB drivers and rebooted - no good. Does anyone have any
ideas please. I can't Restore to before for upgrade as the dates are
unavailable on the calendar wizard. I have IE7 also. My hardware installs
perfectly on my laptop.

Thanks to anyone who can help.

Rob