What anti virus are you using? Wen you use Alt+Ctrl+Delete to open the task manager, what is the performance tab telling you with regard to CPU usage and memory?

Go to the processes tab.locate Thunderbird in the list. What is the size of the working set?

Click on the CPU heading this might be once or twice to get the processes using the most CPU resources to pop to the top. Is Thunderbird the top user? or is there another process grabbing CPU cycles? are there two processes both fighting for top spot? if so what are they?

I've been having the same issue and have chased this around since going to win 10. Anti virus is not the cause that I can see. It just stops working when typing an email. My work around it, type in MS Word, then copy and paste into an email. Not a good thing. Then today, loading images has become sluggish and slow. Again the "unresponsive" notation.

andythebeagle,

I'll send you some doggie treats. Actually, maybe a week after I posted my question, it started working normally again. It seemed that after a few routine (automatic) updates to Thunderbird happened, the problem was corrected.

But don't worry, just keep wagging your tail and sniffing around. But don't howl too loudly. The neighbors don't like that. I'm patting you on the head. You're a Good Boy!!

Oh, I needed that...

Thanx so much for understanding. I'm a happy beagle. I've learned more about TB than I ever wanted to know.

I have this problem too. Process Manager tab shows Thunderbird using 50% of CPU: Firefox using 42%. Still locks up even with Firefox closed.

Using IOLO for antivirus