My computer makes a beeping noise

My family has had this desk top for a few years. It's a Dell. We've never really had any problems with it before, aside from it have such a long start up time. Now for some reason when we turn it on the bottom makes a weird beeping noise. It produces about 3 beeps per second. The screen turns on like normal and automatically goes to the Dell start with the load bar at the bottom almost completely full, but that's where it stops. It doesn't go any farther and keeps making the fast beeping noise. Please help.