When your computer is really messed up, the Blue Screen of Death tells you.
On the BSoD it shows the reason why your computer stopped, generally, you have no idea what it means.
Some BSoD reasons include:
Page_Fault_In_Nonpaged_Area (whatever that means)
Memory_Management (that sounds bad...)
also some .exe files cause the BSoD
your computer could be ok, or it could be dead, good luck
the default background for windows is blue for a reason, dam blue screen of death