Blown channel?

I have an infinity 5760a six channel amp, which worked well for a while but now has an issue which i find very annoying. the four channels for the front and rear speakers work fine but the sub output is where i am having the problem. whenever i hook up both channels and when the bass hits, the entire amp shuts off for about 7-10 seconds and then comes back on gradually until the bass hits hard enough then the same problem occurs. it does this when both channels are being used either separately or bridged. I can use either channel independently of the oither with no problems. I have tried to figure out what is wrong with no luck as yet.