Sub cutting speakers out after certain volume?

I have a smarties sub and amp (i think its 500 or 1300 watt) and after a certain volume around 15 or 16, the whole sound system stops working until i turn the cd player off and on again and i have to turn it down. I'm not sure about the specs but i have it all wired up properly and the fuses are in working order, i don't understand why it cuts out. It's wired from the battery, i have a ground cable attached to the boot catch, wires connecting the amp/sub and wire from the speaker input to the amp. If anyone could help.sort it i'd be very grateful, thanks!