Thunderbird on PC, Windows 10. Lately, I've been getting repeated requests to submit my password for my 2 Shawmail accounts. A little box pops up on my email screen asking to type in my password. This happens several times a day and during certain times, it happens every few minutes. I do not type in my password but check off the box that tells it to use the password stored in the computer and it works. Even when the password line is blank, I don't type in the password but I copy it from another document and paste it. I've changed passwords via the Shaw site using this same method and still I get these requests. Have I acquired some malware lately? I've done a full scan and it came up with nothing. How do I fix this?