Just an update. Removing Bluemoon didn't fix my problems. They soon came back. (worked for just that session)
However, I seem to have fixed IE11 (Running Windows 10 updated from Win 8.1) crashing/freezing all the time. It also seems to have stopped the "are you sure" occurring on Bluemoon as well. (well for two days!)
Note, I tried a few things at once, so I'm not entirely sure if this is 100% what fixed it. But just in case it did, I will put it here for others to try. (IT/admin bods feel free to jump in with advice)
In IE11
Go to "Tools"
Then "Internet Options"
Select the "Advanced" tab
Scroll down to the option "Security" and select "Enable 64 bit processes for enhanced protected mode* "
You have to reboot your PC for these changes to takes effect.
On re-boot I got a message saying some incompatible 32/64 bit add-ons had been disabled
I previously had some add-ons that wouldn't be disabled, but had now changed.
I have noticed the 32/64 bit add-ons which couldn't be "disabled" or changed (for some reason) now say "Incompatible" instead.
CIESpeechBHO class now "Incompatible"
Groove GFS Broswer helper now "Incompatible"
Java plug-In SSV Helper now "Incompatible"
Java plug-In 2 SSV Helper now "Incompatible"
Hope this helps somebody...