Hello, Sorry for my English, but I have big problem. Clean instalation of OS X Lion is without any problem. But instalation/upgrade on Yosemite or Mavericks crashed while loading instalation data, then restart and loading again and crashed again. It is very strange. I have new 500 GB HDD intel, 4 GB RAM. Where could be problem? I did reset of everything PRAM and SMC. PLEASE HELP.