Indeed, I have been using "Insert Shuffled" a lot more over the past few days. Shuffle itself (the playback option) is not enebled, and repeat is set to Repeat All.
Could you describe how you start the playlist or manipulate it ...?
I don't really do much.

Basically I thumb through my database and/or the file browser, and when I bump into (a) song(s) that I want, I pick "Insert Shuffled". I frequently build playlists of over 100 songs this way (I ride my bike a lot now

).
I did check the limits. Max playlist size is at 5000, which exceeds the number I stick in my playlists by a good 4000 or so.
I should mention that I use a Sansa c250.