I am putting together a HTPC using an ASUS P5B motherboard with on board audio, vista,and a Hauppauge Win-TV HVR-1800 capture card.  When running the Media Center my audio for the TV Tuner cuts out within 40 minutes.  This happens for both recorded and live inputs.  I can still play back recorded feeds with audio and all the normal media center audio is functioning.  I'm assuming since the audio cuts out after a certain time that I might be running into a overheating issue.  I tried running it with a fan directly on the Hauppauge board with no luck