|Press and hold the on/off button and wait until the system powers down. Then wait a minute or so and power up as per normal. It will very likely reboot and then go through a file checking routine before booting into the desktop.|
This is a standard method to shut down a system without going through the normal shut down process; not usually used unless the system is hanging - as your appears to be?
You might also - once it has shut down - remove the mains/power adapter lead into the laptop and also remove the battery. Then press and hold the on/off button for about 30secs. This will discharge all stored charges in the system. Then restore battery (and may b, connect mains adapter too) and power up as normal.