Thunderbird asks for passwords every time I open the app, and it also opens a google web page.

I have 8 email accounts. Four of them use my service provider; "@Bell.net", and four of them are gmail accounts. When I open my Thunderbird app two things happen. A Google web page opens asking "Mozilla Thunderbird Email wants access to your Google Account". with a reference to one of my gmail addresses. This web page opens when I shut down Thunderbird as well. Secondly, Thunderbird asks me for the passwords for each of my four Bell accounts. I have tried everything suggested, deleting passwords, deleting profile files, you name it. I've been at this on 4 separate occasions, with this last one lasting 2+ hours. I'm at a complete loss. When I suggest deleting Thunderbird and reloading it, I'm told that may not fix the problem because it would still reference potentially corrupted files. Please help!