Jeffrey,
So far my testing has shown the same as you - with guide data loaded channels drop off my channel list. Without guide data the channels remain - I have tested by setting "time" based recordings on each channel (ala good old VCR land) and I can record as much as I want and the channel info remains fine.
Load guide data in and the channels begin to disappear. It may be a coincidence but it is still worth the Ice guys checking out I think.
Regards,
Shane.