So I recently installed a 120gb ssd in my machine and installed Yosemite. Now when I reboot, I get a prohibition symbol. Basically its a no smoking sign. I have to power off the machine and power back on... So my question is could my sata cable be going bad? It says waiting for root device when I restart. Also I have returned the drive and got a replacement and the replacement does the same thing. Its a 2010 MB Pro 13". Thanks for your assistance.