I have a 2013 Macbook Air that i bought brand new the end of December. It is honestly not used very frequently (until recently) and It's been upgraded with 8 gigs of memory and an i7 processor. After updating to Yosemite, both of my USB drives will not mount and after a long period of typing and hitting certain keystrokes with the caps lock key, my entire keyboard and my mouse will freeze up and i have to hard shut down my computer. I was unable to reboot the NVRM for some reason on Yosemite so I still have no fix for this. Does anyone have any ideas to help me? GAR. So frustrated.