I've seen a few questions and mentions regarding Assert Handler errors within Indiana Jones and the Infernal Machine. While I'm not entirely certain how to fix all of them, I have figured out how to fix the one I got stuck on.
The introduction movie for the Palawan Temple would begin but would freeze just prior to Indy breaking through the brick wall, and the following Asset Handler error would appear, "sithCogFunction.c(3211): (pThing->type== SITH_THING_PLAYER) II (pThing->type == SITH_THING_ACTOR)".
After restarting the level several times, the same thing would happen. I would even play the last part of Palawan Volcano over again. However, nothing worked. Until I tried this...
I went to the C: Program Files\Lucas Arts\The Infernal Machine\Resource\Cog folder and deleted the Palawan Temple Introduction cog file (TEM_IntroCut.cog). I then went to the C: Program Files\Lucas Arts\The Infernal Machine\SaveGames folder and deleted the Palawan Temple saved game that the game automatically saves for you at the beginning of every new level. This was titled "start_07_TEMPLE.nds".
After that, I played the last part of the Palawan Volcano over again and wallah! I was then able to get through the Palawan Temple intro movie without a hitch!