i just recently downgraded from .190 back to .185
this is what i did and it worked w/ no problems...
-1st i backed up my phone
-then disconnected phone and closed Desktop Manager
-go to control panels>add remove software & delete Blackberry 9000 software
-download .185 from BlackBerryForums
and save it on desktop
-open up the newly saved .185 on desktop and install .185 on computer
-open Desktop Manager and connect phone.
....Then you will be asked to install .185