In case anybody else has run into this, this is from a newsgroup posting from "Seth S." about how to overcome issues with Word after PD11 is installed. The problem is that Word loads the PowerDesigner plug-in by default (everytime you use Word), not just when PowerDesigner needs it. For me it's been a real issue because I use Word as the editor for Outlook, so it keeps getting loaded when I'm in Outlook as well.
One minor correction. That key shows up for me under HKEY_CURRENT_USER, not HKEY_LOCAL_MACHINE as the newsgroup post indicated.
The workaround is to change the LoadBehavior of the DLL in Word
LoadBehavior should be set to '3' and you must set it to '2'. After that Ms Word will not load the DLL anymore.
NOTE: The add-in remains listed in the Global Template and Add-in box and the contextual menu named 'requirements' is still on the menu. These things will be address in the cr 376227.