Need Help With Mozilla Firefox

Hey Guys just ran into some trouble with the firefox portable in P Apps.
when i start firefox it gives me this message:

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

1. Firefox is not running when this message appears not even the process.
2. So this leaves me with restarting the system. Even after restarting i face the same problem.
3. Last thing i did after using Firefox was to creat a shortcut from Portable Apps to Pstart, and it did start but after the first initial startup from Pstart menu it din't start the 2nd tym thus show the above message.

I also reinstalled Firefox but still same problem.

Thanks.
RK