vagabondo, You are not alone. I too have seen this a few times. My current channel count is 23. It all happened when i went to add Hulu+. So, I started dropping channels like 5 at a time. I was finally able to get H+ installed. It happened again when i tried to add some of last weeks new channels. Again i removed a few until it gave me enough space.
Some unique things about my roku hd are as follows, and maybe you share some of these.
* I have myMedia installed as private channel in developer mode (Old version), as well as the newly released version in non-developer mode.
* I have always had issues with Google voice channel by nowhereman (A.K.A RokuChris) not sure if related.
* I move my device from TV to TV wherever we are. Not sure if that matters.
Anyways, I would like to see it fixed, but i really only use roku for a few channels of which i can get currently. I am starting to believe that certain channels are probably large in program size, or the operating memory is getting filled up with some channel data. I am no developer though, just an IT manager, so all i can so it add to the list of symptoms on my side. Hope this helps to identify the scope of the issue further. Happy Turkey Day