Hi Minnow, I am also running Windows 7 (x64). The fact that your problem is intermittent and you can't identify any kind of pattern makes it difficult to suggest fixes for your problem. However, a thread at https://bugzilla.mozilla.org/show_bug.cgi?id=565171 suggests that this is a five-year-old bug in Thunderbird that is still alive. The same thread indicates that a permanent fix for users is to switch over to an IMAP4 account from a POP3 account. Setting up an IMAP account is no more difficult than setting up a POP account--you will probably use different ports, and you might use different incoming and SMTP server addresses. In fact, you should be able to set up an IMAP account in addition to your POP account with the same email account. I have my personal email account with indra.com set up that way on my desktop. I have the POP account set up so that emails are left on the server for a limited period after they are downloaded. This way, when I'm away from my desktop, I can use laptop IMAP to see my mails, while still having the convenience of POP for my desktop (some of my favorite add-ons and utilities require POP). In this way, you can test to see if having an IMAP account makes a difference, and you can also look for a pattern in with problematic emails in POP. If you find the IMAP account works for you, you can copy over the local folders for the POP account to your local folders for the IMAP account and delete the POP account. If you don't want to use IMAP and want to continue using POP, I would suggest that whenever you get the RETR error message, use the Talktalk web mail interface and look at the messages in your inbox (or it might be in your junk folder) to see which of them is being problematic. In this way, you might recognize a pattern--for example, the messages are all from an Outlook client, or they're all from yahoo mail, or they all have large attachments, or etc. Then it might be possible to suggest a fix. However, as indicated in the thread mentioned above, if you are experiencing the same bug, there might be no way to fix it. If you decide to modify your account settings, I would definitely use MozBackup to save your emails and configuration beforehand. Then it is an easy matter to recover your old setup. Hope this helps, Norio