stereo cutting out

i just recently purchased a Pioneer cd player 45x4 output, and everything is hooked up right and taped with electrical tape. when i turn up the stereo to a certain point it will cut out, and then come back on, and it will continue to do this unless i turn the volume down. i'm thinking its the speakers, but the two front ones are 45W Bolts, and the rear is a shitty little sub, that says it can go to 120W. any help would be appreciated