Ubuntu 14.04 freezes when during or after opening firefox

Ubuntu 14.04 freezes during or after opening Mozilla Firefox. I have installed Ubuntu on two computers, one is в двойственный Windows boot with 7 and the other I just did в strait install. The same problem happens on both. I am only able to get двойственный Ubuntu to run in recovery mode on the boot computer. The other one doesn't give я the option for recovery mode.