AT&T Midwest → can't access my email with windows live mail

I am using Windows Live Mail, recently upgraded to version 2012, on Windows 7 x64. For the last day I have been unable to access my email with WLM, although I can access it with the web site. The error message reads: An incorrect password was entered. Server error: 0x800CCC90

I went into my profile and changed my password. Then I verified that I could access my email on the web site with the new password. But I still get the same error when using WLM.

Let me emphasize:

1) I cut and paste passwords so it's the same for both, I'm not mistyping anything.

2) I'm using the recommended server settings (inbound.att.net, port 995; outbound.att.net, port 465; SSL required for both). I've triple checked this.

3) This problem did not start immediately after upgrading WLM: it worked for a couple of weeks. The problems started yesterday.

It is working for me; an '@att.net' account and 'imap.mail.yahoo.com:993'.

But I am no longer an AT&T customer, and have not attempted to use 'inbound.att.net:995'.