FirefoxCP WebExtensions stopping web pages being loaded
In the last couple of days, Firefox has stopped loading any web pages on start-up. When I look at the activity manager on my mac, I see a FirefoxCP WebExtensions task right at the top of the queue using 99 - 100% CPU. When I cancel this task, Firefox immediately starts loading pages as normal. There are also FirefoxCP Web Content and FirefoxCP Privileged Content tasks, but they don't seem to be causing any problems.
I'm running Firefox 78.0.1 on a mid-2012 MacBook Pro with MacOS High Sierra 10.13.6. My only extensions are Adblock Plus, Browsec VPN and Greasemonkey. My Plugins are OpenH264 Video Codec, Shockwave Flash 32.0 r0 and Widevine Content Decryption Module
Any help greatly appreciated.
Modified by mark_woronowicz