My Computer Smells Like Its Burining?

my computer has developed a burning smell. when i turn it off it smells like smoke. recently also my computer has been crashing, i can only move the mouse and this only happens whilst avg is scanning, because when i return the clock is stuck at the time it crashed. When i performed a disk check it said i had been suffering blue screen errors. so i took the case off, gave it a hoover and it still smells, please help...