I've been looking at this for a few days but for the opposite reason I wondered why dullan host was not running because it usually is the reason being still unknown but it gave me a chance to research this into such great lengths that the answer was so simple and was staring me in the face.
I'm also surprised no one mentioned this for this fix it could not be more simple if it tried.
I'm on windows 10 so this will only work on windows I do not have linux or know how it works entirely so im sorry I cant help you there.
To fix the Dullahan host and its many errors all you need to do it locate your control panel the best or quickest way you want to do this if you dont already know theres a bar on the lower left hand side type in control panel and click it.
Once in control panel type in top right hand search box firewall once in firewall click allow app through firewall click change settings go down to dullahan host and untick it on the left hand side column only click ok and done.
Restart your browser etc and done.
You do not need to remove this service and my advice is to not to remove anything from the browser or otherwise if you do this I cannot help you please do not go deleting things you do not know what they are do not go multilating your viewer so you cannot access anything
Doing things this way will let you have everything you want at no risk of damaging the viewer itself
I hope this helps someone have a great day
P.S ( If you have let firestorm through the firewall I also suggest unticking this as well )
If you are having problems running it please add it to your anti-virus whitelist, and it, should run fine.