I'll apologize in advance if this has been answered already, but I looked in both the Mint and Ubuntu forums and tried everything I found there, with no results.
I'm running Felicia with Xfce on an old IBM Thinkpad T20. It runs quite well, no complaints. The problem comes when I try to stop running. I see the same thing no matter which shutdown method I use. I can use the Menu and Quit, or I can open a terminal and type
sudo shutdown -P now. In either case, the screen immediately goes black, and the system will stay in that situation longer than I have patience to wait. There is no text, no blinking cursor, and no progress bar, but I can see that the screen backlight is still on behind the black screen. Eventually, I have to hold down the power button for several seconds to get it to shutdown. And then, it's not really shut down. I can leave it in this state under my bed when I go to sleep, and I'll invariably find that it's powered itself back on, and then gone to the same black screen condition when I wake up. Also, when it's trying to shutdown as described above, I've tried to get to a terminal by typing CtlAltF1, or F3, or anything and nothing happens.