Random recordings

I occasionally notice that my HR24-200 does random recordings.. I'll look in my Playlist and see either partial or full recordings of shows that I did not choose. Sometimes, the titles will be of shows that I do watch, but the recordings are actually of other programs. These recordings seem to happen most often overnight... 2am or so and often seem to be infomercials. I know that neither me or my wife set these programs to record. I review my ToDo list fairly often so that I know what will be recording in the next few days and remove anything that I don't want to record such as items on Series Link that are not actual new episodes (but D* doesn't know any better). Anyone else have this random recording issue and know of a fix? I'm guessing it is a program in the D* system somewhere.