Thank you for taking the time to report this bug and helping to make Ubuntu better. May you try to run gnometris from the command line and see if there's any output when you get the system hang? what video driver are you using?
Thank you for taking the time to report this bug and helping to make Ubuntu better. May you try to run gnometris from the command line and see if there's any output when you get the system hang? what video driver are you using?