Please check https://help.ubuntu.com/community/RestrictedFormats Go to section Macromedia Flash (although yours is gplflash) and read the troubleshooting part.
If that solves your problem then let me know. -- Firefox hangs with Flash https://launchpad.net/bugs/50449 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
