Assuming you run a Windows o/s...
I bet your CPU is running at 100%. My laptop, and ocassionally others that I've seen, have an issue where some processes cause the CPU to run at max output continuously. Open your task manager (ctrl + shift + esc), click on the performance tab, and see if it's at 100%. If it is, click on the processes tab, click twice on the CPU column to sort by processing usage, and end the culprit (right click on it, click end process).
If this is the case, figure out what program did it and be aware of it in the future.