Mark's channels have disappeared from his Hauppauge tuner. What happened? Leo says that the FCC has made stations shift frequencies, and have advised that users rescan for missing channels. Check out TVAnswers.org for when and how to rescan. There's more information here - https://losangeles.cbslocal.com/video/4040289-cbs2-rescan-day/. But it may also be a Hauppauge issue.
Frank bought a Sony XBR 800e. Three weeks after his warranty expired, it started having trouble. Leo says that while the warranty is expired, it's close enough that if he calls them and pleads his case, Sony may be willing to extend the coverage and fix it, and it's likely just a tuner that's gone bad. The other option is to use a third-party tuner. Leo recommends a TiVo or Channel Master product.