my cpu won’t stop beeping and keyboard flashes and stops working

Hi I have a Dell Dimension 2350 2 days ago it was working fine all of a sudden the cpu starts beeping it starts out slow them beep fast and then the keyboard lights start flashing and then the keyboard stop working and the mouse does that mean the serial port for keyboard and mouse are going bad or is it another issue i’ve never had this problem before it is almost 4 yrs old i have to usually shut it down cause it’s driving me nuts i’m not sure on what to do please any ideas or help thank you michelle