After messages appear in Inbox, I cannot open them until the progress meter at bottom of page finishes. What is this meter checking? All mail from other gmail accounts are forwarded to one account, and that is the only account I have T'bird set up to check. Is T'bird waiting for virus check? Or waiting to put messages in other folders, like All Mail, Spam? etc. I asked this question elsewhere on forum as part of another question, but did not find answer so I am posting separately here. I have tried opening T'bird in Safe Mode with no add-ons loaded. Didn't make a difference.

Thanks, David