I've been a user of Thunderbird Portable for many years, and this is a recent problem.
My current Thunderbird Portable is Version 91.5.1 (32 bit).
Sometime a couple of months ago, after I believe there was a Thunderbird update, I began to have a problem when trying to print an email message from Thunderbird. The "Preparing Preview" screen opens, and then never proceeds at all. There is a spinning icon by the words "Preparing Preview" - and on the right side of the screen is the word "Print".
It totally fails every time - no matter which printer I am using, and I have several. The printers are all connected with ethernet connections - and all of them work perfectly with printing from other programs. It is only Thunderbird Portable that fails to print.
As a test, I removed the USB with the Thunderbird program and put it into two different computers - and in those computers the print command works normally.
My PC is a Windows 10 Pro desktop, with i7-10700 CPU at 2.90 GHz, 16 GB ram, and 64 bit operating system and processor.
I have attempted to solve this by downloading a new copy of Thunderbird Portable. But I had many problems trying to set it up correctly with four different email addresses - I suppose I could attempt to do that again - but I'm really hoping for a simpler suggestion.
Thanks for any ideas anyone might share.