powerbook will not start up, it just beeps at me


hello all,
have had my 15' powerbook g4 1.5 for just over a year. i was using an i pod the other day with it and was loading some tunes on to it. suddenly the computer crashed, completelt froze up. nothing would work.
i took out the battery and tried to restart the computer, all that happens it the screen flickers, then nothing for a few seconds. then the conputer beeps at me three times and flashs the light that is on the screen release button at me.
please help me in the right direction.