オリジナル投稿者： Dan ,
Your system maybe just fine! Apple requires a full restart during the upgrade process a few times as the there is a firmware update as well as an OS update (I've had systems do four restarts to apply everything). The other problem I've seen is a HD which has problems go into a tailspin of restarts as the firmware update is not able to complete. The only way to overcome this is to boot up under an external drive or use a second Mac system to fix if possible your drive using Disk Utility by putting your system in Target Mode. Otherwise you may need a new drive.