I am trying to upgrade to Lion from Snow Leopard. After beginning the download/install process from the Mac App store everything seemed normal. However after about 20 minutes my entire MBP is frozen. Trackpad and keyboard do nothing, and the mouse pointer is not visible on the screen.
The screen is stuck at where it was before: looking at the Lion page in the Mac app store.
It's now been about 15-20 minutes of waiting at the frozen screen. Is it safe to restart the computer and start the process anew?