An anti-scald tub/shower valve will do this...it is normal for it to shut down when you don't have equal pressure in both lines. This is called a pressure balance valve, and is the most common anti-scald method used. As to why you can hear what appears to be water flowing, that's another issue. If, when you run cold at a faucet, it is mixed with hot, or your hot is tepid, then you may have a defective cartridge in a single handle faucet somewhere that is allowing the hot and cold to mix. Solution is replacing the worn out or defective cartridge.