I'm thinking this right here has something to do with the Interrupt Request which is what IRQ stands for. Every piece of hardware including the mouse and keyboard have a set IRQ and if another component is also set on it, this would cause the system to not function.
So exactly like the screen said, SOMETHING in your system isn't seated right, or simply shouldn't be there.
To to troubleshooting to find out what component it may be you gotta completely take out the motherboard and put it something non-electrically conductive, plug in only the essentials, ONE stick of RAM, the keyboard, and video card, also plug in the little 4pin computer speaker that gives off that BEEP so you can listen for any possible beep codes. If the computer boots up, then start adding in pieces until you find the one that's causing this problem.