After looking at the MEL for that script, my only hunch is that somehow you're selecting the transform node instead of the shape node somehow, but that's a shot in the dark. When in doubt with Maya, either delete or rename your prefs folder and restart. That will force Maya to re-create the default preferences.
Open the script editor, does it give any more info after that error line? Also, did you install any custom scripts? You can use a temporary work-around and use the F8-F11 keys for object/vert/edge/face select modes.