Hi, I had this problem in Mavericks and after a successful update to Yosemite, it still continues. I am using my thunderbolt SSD as my main drive, so yes, OSX is installed on it. I run my mac 7/24 and sometimes I find pop up windows stating "XYZ software prevents OSX from restarting". How can I fix this problem, how can I check system logs (My account has admin rights). TIA!