LastPass password manager for Firefox (Mozilla based browsers) updated to 4.42.0.2 today. I immediately started having issues with Tenforums and the auto logon function. Invalid username/password alert. Manually entering ID/PW is fine, but auto thru LastPass may cause you problems. Continued retries on the failed login screen after 5 attempts will put you in a 15 minutes wait cycle to try again.

I reverted back to the previous version 4.41.1.4 and everything cleared up and back to normal.

Previous version is on Firefox Extensions site:

LastPass Password Manager version history - 25 versions – Add-ons for Firefox (en-US)

If you are having similar issues, or others caused by this update, remove 4.42.0.2 and add 4.41.1.4., set the "update" mode for LastPass extension to OFF.

Leave 4.41.1.4 active until a new version is released.