Help! I just got my Windows7 upgrade in the mail yesterday and started the installation. After it got going I took off for the day, and when I got back the screen was black with only the cursor visible. I tried restarting, and got a screen telling me that startup was preparing the system for first use. It stayed there from 6:30pm until 9am, so I restarted again. It says the windows 7 is starting, but then goes goes to a black screen with only a cursor. Can anybody help me???