Hmm...
Gleem City has some sort of puzzle with rotating the 4 planets of the Roib system that I can't solve. Is the answer in another level that I haven't beaten yet?
Last Outpost, another level that has Super Dupers, also has random crashes.
I think it's safe to say at this point that the crashes are because of something in the Super Duper patch file! All the other levels have been stable.
Also, some general comments... there's a lot I like in this mod. Great premise and story, evocative art, imaginative enemies and locations.
But I also feel the level design in this particular mod would be made a lot more enjoyable if Keen had a damage bar (like in Cosmo or Hocus Pocus) rather than a one-touch death system. A lot of the enemies are like the ones in Keen 3, who follow Keen around, and have a random rather than predictable pattern. Sometimes they get into a spot where they're extremely difficult to avoid (for example, those rich pricks with the big laser guns, they're like those scary floating robots in Keen 2 except they follow Keen around even when he's not in their line of sight, and sometimes if they fire when on the edge of a platform, they fall down onto the platform below. This can be a good thing, or it can make getting past them really difficult). I also really hate those "guano from above" pipes that wait until Keen is beneath them to strike. Lots of surprise difficult to avoid deaths there.
Oh, and it can be hard to tell where the actual edges are of debris in the poison river levels, so it's pretty easy to miss and fall in (I love the art for them, but it's not easy to see where the platform is).
Sometimes in the second half of the game, the level designs have been a bit too big and confusing for me to keep track of in my head, and the fruitless backtracking was frustrating, so I resorted to using the endless jump and godmode cheats to quickly find where exactly I'm supposed to go next, or which particular part of the level a switch affected (after which I turn the cheats back off again). I've also become really paranoid of surprise deaths and save frequently. I kinda wish that saving and loading could be done with a single button without exiting to the menu (say, to the default save/load slot) and without the music restarting every time I do it. I really like a lot of the music in here, and it's a shame that it keeps getting interrupted during gameplay.
Also, I've enjoyed the occassional hidden, easy levels, like "a forest of bugs" or the "dump".