I've encountered this same problem, only it started before DK17 (~DK05 I think). No problems removing DRM APKs on 2.1, but on 2.2 mp3 ringtones caused forcecloses. Even opening the same file with the music player (not in the settings app) forceclosed. The problem went away when I reinstalled the SisoDrmProvider apk, the DrmUA one didn't seem to be necessary, nor did it seem necessary to have any drm services running.
I wonder if froyo handles data for removed application differently than eclair... On eclair, I heard of some people being able to remove the DRM APKs as long as they didn't clear the data (I always forgot), perhaps froyo deletes the data when the DRM APKs are removed?