Issue: Quicktime plugin taking over Flash in Firefox

My friend Amy had a problem on her XP system viewing Flash content on webpages in Mozilla Firefox after installing Quicktime although the webpages appeared normal in IE 6; not sure about IE 7. Wherever a flash object was supposed to appear, there'd be a big "Q" with a question mark. I went into Quicktime Preferences and deselected everything except .MOV files, but that did not solve the problem, so I went looking for an answer to this on the web. Here's what I found (the last step of removing the Mozilla npqt*.dll files is what worked for her):

Quicktime plugin takes over Flash - MozillaZine Knowledge Base

If you see a Quicktime symbol with a question mark where the Flash content should be, it means that Quicktime has taken over handling of Flash files. On Windows, open Quicktime Preferences (accessible from the Windows Control Panel), select the Browser tab (or the "Browser Plug-in" drop-down menu option in Quicktime 6 or earlier) and select the "MIME settings" button. Uncheck "Flash media" or "Flash file" under "Miscellaneous" and "FlashPix" under "Images", then restart your browser. On Mac OS, go to the Quicktime System Preferences and deselect the corresponding MIME types, which are found by going to the Advanced tab in recent OS X versions [7]).

If the problem persists, remove the file "pluginreg.dat" from the "Firefox" or "Mozilla" folder in the profile folder location. Additionally, remove any "npqt*.dll" files found in the Mozilla Suite or Firefox installation directory's plugins folder. [8].