i think you mean crackling (fuzzy) not cracking (good)
it may be that as with a normal TV the signal is not strong enough so you get the static that you get with a normal TV if the signal is low
if the signal is ok try updating the sound driver for your computer as it may not be fully compatible and most sound card manufacturers keep on releasing updates as software changes and so causes an issue so check out your computer manufacturers website and also the manufacturer of the sound card themselves for help
email me if you need more help on this
also go to the Hauppauge website and update your TV tuner driver even if it's brand new as updates may be available for that also
failing that check the connections in the computer make sure al is tight and secure