Alright, well, that's something.
Now, you might want to restore your computer to a previous state ( before it started freezing.)
So,
First, open the control panel. Then, click on "System and Security".
On the left, click on "system Protection" link.
Click on "system restore"
Follow the instructions.
EDIT : replacing the motherboard is the worst thing you can do right now.
EDIT 2 : BUTTERFLY!!!!!!