Firefox 12 Problems

[TheHitMan-1973]

I am having mega problems with Firefox 12 . I keep getting this error message when clicking on item

"Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system"

Even restarting still sometimes getting error message

Any ideas

 

[Azuse05]

Task manager > kill process.

 

[TheHitMan-1973]

Task manager > kill process.

Done that , still get "Firefox is already running, but is not responding. To open a new window, you must first close the existing Firefox process, or restart your system" when trying to re-launch again