Well I went there and there is little information there to identify the real cause.
It isn't good to refer people to another forum for any information anyway as it isn't easily accessible or easy to follow later in the thread. So I would suggest you start again here.
I'm somewhat confused by these comments from the other forum:
There have been some reports of problems with Avast! and the latest Windows update blocking email. That would be the first place to look. Also make sure that ZoneAlarm is still allowing Thunderbird.
Well here I have been for some time and this is the first I hearing about this windows update blocking email, when you say it was working till this morning and there haven't been any windows updates today nor avast program updates.
You also mention:
Like i said, it was working fine until this morning. She is running version 1.5.0.5 TB. It seams that this is a common problem that other users have had and I have done everything that was told to the other users to no avail. Also we set up the accounts in Outlook just to make sure and they work and they did so it is obviously a TB problem.
So it works with MS Outlook (mind you Outlook uses the Outlook/Exchange plug-in and not the Internet Mail provider) and gmail (which isn't monitored by avast, secure email) but not Tbird, so there is still some conflict where it lies is the problem. Disabling the web shield could well have the effect of letting things through but it may not be the true cause, just removing one part of the problem/conflict.
What is the exact error you get or post a screen shot ?
Unfortunately I don't use Tbird so I can't test this, I use OE6 SP2 and XP Pro with no problem. Are you able to try it with another email program that will use the Internet Mail provider, like OE ?
Tbird is a fairly popular email client and many on the forums use it if this were truly as big a problem as is being made out it would be all over the forums but it isn't.
It seams that this is a common problem that other users have had and I have done everything that was told to the other users to no avail.
I would like to see which threads you refer to, if they are the same problem then the same suggestions should have in theory also worked ?
I'm not trying to say this isn't an avast problem, just trying to get to the bottom of the problem.