TivoHD HD Channels come in, but not SD

[joshdev]

For some reason my Tivo will go into this mode sometimes that will cause it to stop recording and displaying standard def channels. If I go to a live standard def channel the screen is just black. For any program that was recorded during this change, it shows only a partial recording. All of my HD channels still work and record fine though. Any ideas on why that might be occurring and what a possible workaround is?

--Josh