Firefox 43 issue of not allowing install

Well I had the x-notifier on my browser for years now and love it. Today I start Firefox and everything was working fine until I believe my browser updated. At that point I get told that some add ons are no longer working. I clicked on the notification to see what it was talking about it was only showing "Microsoft .NET framework assistant" and it said I could restart it or something along those lines. I clicked the restart Firefox button to try to fix it and when it restarted my x-notifier was now no longer on my browser header like it always was in the past and on the extension page where the .NET thing was it now showed the x-notifier as one as well.
I continued to try to fix this but didn't get anywhere. I assumed it needed to be updated or something but when I tried to search for x-notifier it never showed up. I did see the lite version so I downloaded that one to see if it would work. I showed up on the header like the original one was before but it also didn't do anything. So I uninstalled both of them and tried to search them again. This time the original x-notifier finally showed up and it allowed me to click the install button. I did this and it said that Firefox needed to be restarted to finalize it. I did this now 10 times but it will not install it no matter what I do. I can only download it and then that is it cause it will not go any further.

Anyone else having this issue? I have no way to currently access my email accounts as I have long forgotten my passwords to them. LOL! Only thing I will be able to do is click forgot passwords most likely to access them again. What is going on with the x-notifier?????