Tiles and transtions not loading

Question

When I attempt to put a title or transition into my film, it shows up as a glitchy/buggy black screen. I have restarted iMovie and tried starting new projects but I cannot use any title or transition effects as it just shows up as a black frame on my screen. I have the latest updates as well.

Answer 1

-> Tap '''ALT''' key or press '''F10''' to show the Menu Bar
-> go to Help Menu -> select '''Restart with Add-ons Disabled'''
Firefox will close then it will open up with just basic Firefox. Now do this:
-> Update Firefox to the latest version by going to Help Menu -> About Firefox -> click '''Check for Updates''' -> if an updated version is found then download the latest version and install it. After that follow these steps:
-> Update ALL your Firefox Plug-ins https://www.mozilla.com/en-US/plugincheck/
-> go to View Menu -> Toolbars -> unselect All Unwanted/Incompatible Toolbars
-> go to Tools Menu -> Clear Recent History -> '''Time range to clear: select "EVERYTHING"''' -> click Details (small arrow) button -> place Checkmarks on '''Cookies, Cache''' -> click '''Clear Now'''
-> go to Tools Menu -> Options -> Content -> place Checkmarks on:
1) Block Pop-up windows 2) Load images automatically 3) Enable JavaScript
-> go to Tools Menu -> Options -> Privacy -> History section -> '''Firefox will: select "Remember History"'''
-> go to Tools Menu -> Options -> Advanced -> Network -> Offline Storage (Cache): click '''Clear Now''' button
-> Click OK on Options window
-> click the Favicon on SearchBar -> click '''Manage Search Engines''' -> select all Unwanted Search Engines and click '''Remove''' -> click OK
-> go to Tools Menu -> Add-ons -> Extensions section -> REMOVE All Unwanted/Suspicious/Incompatible Extensions (Add-ons)
-> go to Tools Menu -> Add-ons -> Appearance section -> REMOVE All Unwanted/Suspicious/Incompatible Themes (Persona)
-> Restart Firefox
You can enable your Known & Trustworthy Add-ons and Themes later. Check and tell if its working.