Hi,
Un-installing & re-installing the PROGRAM will not usually fix any errors, as most corruption/s occur in the PROFILE.
So...A new Profile may help out here...
Ref; >
http://kb.mozillazine.org/Creating_a...efault_profile
The latest version is 67 & a few "minor problems" have surfaced.
Nothing too dramatic but if you strike problems, then go to the mozillaZine forums.
>
http://forums.mozillazine.org/
We are always glad to help.