I recently encountered an issue - after installing BitDefender - where Thunderbird 24 could not download e-mail, Every attempt resulted in a "suspicious filer' or "not enough disk space" error.
Outlook 2007 - for business-related e-mail - performed.
I could log into my ISP and review the e-mail via the web mail feature (Comcast) - which I normally do in order to "Pre-delete" unwanted e-mail. All good.
But - still couldn't download.
I uninstalled BitDefender and then my Thunderbird mailbox got "lost".
I downloaded/ reinstalled T-Bird 24 - reindexed and got the mailbox working.
However ---- my desktop or task bar shortcuts for T-Bird always open up a "new" T-Bird window - as if I don't have a e-mail account or mailbox, etc.
However (#2), I can go to C:\ProgramFiles (x86)\Mozilla Thundbird, locate the exe file - choose "run as administrator" and all works properly.
What am I missing?