Sometimes my email headers get crossed with bodies of other emails (next in the list), so how do I stop this from happening?

Question

We use Thunderbird with the email header list (Inbox, etc) in an upper pane, and the body of the highlighted email in a separate lower viewer pane.
We compact files whenever asked by the software.
In a long list of emails, I click on one header (at the top of the list) to view it in the pane below. Once in a while, the headers get mixed up and do not preview the proper email in the viewer pane.
I will highlight and view an email, and then delete it. When this glitch occurs, the body of the deleted email appears in the lower pane when I click on the next email header in the upper pane list. The viewer pane should be showing me the new body of the just-highlighted email, but instead it shows the deleted body of the previously-viewed email. Once that new header is clicked, and the wrong body appears in the viewer pane, the proper email body disappears forever. I have to call my customer to have them resend.
If I click on other emails further down the list, the same body (of the deleted email) continues to show up each time, and all the correct bodies of all the clicked headers are gone. So, phone calls have to happen to ask all the affected emails to be resent. (So, we have learned to stop as soon as we see it happen the first time.)
The only way we have found to fix this is to close Thunderbird, and then reboot the computer. When Thunderbird is re-opened, the problem goes away. But any lost email bodies are permanently gone.
We can't seem to find any strange set of events that make this happen. It appears random, and varied. Sometimes every week, sometimes not for months.
This happens on 2 computers. One is a 2 year old PC (Compaq), and one is a 3 year old HP Probook laptop. Both currently using Thunderbird 24.5.0. Both run Windows 7. Both have lots of memory. Both are very stable machines with very few problems. Seems to be more prevalent on the Compaq desktop than the HP Probook.
Please help.
Thanks in advance.

Answer 1

Do you organise your email into separate folders, or do you just let it accumulate in the Inbox?
I would strongly advise you not to let it sit in the Inbox.
When you see this happening, try right-click on the affected folder, select '''Properties''' then '''Repair Folder'''.
Large folders (actually, a folder in Thunderbird is stored as a file, so it is sensitive to file size limits set by the underlying file system) can be problematic. This is one reason not to let messages collect in one folder. I use Thunderbird's Archive folders so that accumulated mails over several years can happily coexist because they are effectively stored in many small folders. No single mail store folder then exceeds the 2GB or 4GB sizes that have been known to stress the OS. I appreciate that current builds of Thunderbird and a modern 64-bit OS should be able to cope, but practically I find it slows down when given huge files, so I err towards a pragmatic solution; a large number of not very big files.
Archives are searchable, and a Saved Search folder can give you a virtual composite folder allowing access to the entire Archive.