Talktalk is the main provider - talktalkbusiness.net
Talktalk e-mails are re-routed via 1&1 into my web domain, jamesaccounting.co.uk.
I have talktalkbusiness, jamesaccounting.co.uk and gmail accounts set up within T'bird.
The problem began about a week ago. Online research suggests that it's a common issue for version 34.1 which I upgraded to a few weeks back. Prior to that, I'd never exeperienced any like this in 10 years + of using T'bird.
Sorry to take so long to reply. Had gone home by the time your e-mail came in last night and had to see a client this morning.
Yes, remote screen sharing will be fine.