After my install of SL on my MacBook, I'm getting a blank desktop screen when it starts up. Every once in a while I'll get the log on screen, but when I try to log on it gives me the spinning ball of death. I can boot my laptop with safe mode, but thats about it. I have restarted... reinstalled SL.... Disk Utilities... I can get my MacBook to launch into safe mode fine.. but not any other way.