After turning computer off/on because it froze, chkdsk was run, system started normally. Only 3 emails left out of 6,000 in inbox. The email counter stated only 3 emails but had some symbol (asterisk?-couldn't quite see) in front of the three. Address book ok, saved mail only 2 emails left, drafts ok. Not sure why this happened as I have done this exact procedure before when the computer froze and there were no problems when I restarted, chkdsk was run and Thunderbird came up normally with no issues. I have the program updated automatically so it should be the most recent version. There are two email addresses/accounts on this Thunderbird account and the one with the problem is the secondary one. The primary account has no issues.