Enter about:support in the address bar and click the Verify integrity button in the Places database section. It should produce a log, paste it here for analysis.

> Task: checkIntegrity - Unable to fix corruption, places.sqlite will be replaced on next startup > Task: checkCoherence - The task queue was cleared by an error in another task. > Task: expire - The task queue was cleared by an error in another task. > Task: vacuum - The task queue was cleared by an error in another task. > Task: stats - The task queue was cleared by an error in another task. > Task: _refreshUI - The task queue was cleared by an error in another task.

Try to restart it once or twice.

This error showed: "The bookmark an history system will not be functional because one of firefox's files is in use by another application. Some security software can cause this problem."

It looks like a security software quarantined this file, or something like that.

or there's a conflict with the antivirus software using the same file.

I uninstalled McAffe off my laptop and followed the instructions for creating a new profile and everything works fine. The instructions for creating a new profile are located at: https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles