Strange problem with firefox

I was using my Firefox portable when it told me to update, which i did. When i updated and restarted firefox portable, it never opened up again. When i try to open up the program manually, it says "An error has occurred while trying to launch this application." When i try to uninstall it, it just tells me "uninstall of firefox_u3_1.5.70_en-us.u3p failed." I can no longer safely eject my usb drive now since it says theres an application running still. Any suggestions?

[Firefox for U3 is discussed in the U3 Apps forum, not the Firefox Portable forum; Moved there for you by Moderator RM]