RESOLVED: Hello Last night I tried starting up my Macbook pro 15" (early 2009). It is running Yosemite 10.10.2. The mac started up as usual but locked up so I did a hard reset with the power button. Upon restarting, I am greeted with the usual apple logo and load bar just below it but about halfway through I get the 'prohibitory' sign (circle with cross bar sign for no entry). I keep getting this restart after restart. I formatted an external hard drive using another mac to perform as a boot up disk for Yosemite and plugged it into the macbook. I boot to that and *sometimes* am able to get to disk util. When there, the internal hardrive is not showing up at all... thus I can't do any disk repairs with this method. The HDD is spinning, I confirmed this. It seems to be a read issue. Any thoughts on what I should try next?