I had an OEM version of Windows 7 Home Premium x64 installed, and one day my windows started hanging after the windows logo (when the login screen would appear). I hadn't installed or updated any drivers. After being unable to fix the problem through restoring to a system image, startup repair, etc. I reinstalled Windows 7 x64 from a clean iso (no OEM ware). This meant I was missing some drivers. I downloaded the drivers from the Lenovo website, and after installing the video driver, the problem occurred again.
The system does however work fine on Ubuntu 12.10 (Linux).
Using: Lenovo IdeaPad Y560
Windows 7 Home Premium x64
ATI Mobility Radeon HD 5730
Update: I tried plugging in an HDMI cable and unplugging it, which fixed it for about a day. However, while playing a video game, the screen froze, and I was forced to hard reset the computer and the problem happened again.
I tried the HDMI solution again but it doesn't work. My TV, which the cable is connected to, reports a screen resolution and refresh rate outside my range. I can't change it from Monitors, it's stuck at "Use the hardware default," and the registry didn't seem to help either.
For some reason, the laptop would boot without the AC plugged in. I changed the power plan settings on AC to match the ones on battery and it worked for a little bit, until my laptop crashed again. It no longer boots on or without AC.