Okay, more progress! By adding -diag to the published version, it created a log file. Both these issues pop up occasionally, but they are not the cause of the crash, at least, it doesn't crash when these are reported.

Material #DEFAULT undefined 1 textures
Material PORTAL_001 undefined 1 textures

These happen when I switch camera modes, and the texture gets defined through a script, so I don't think these are the problem, since switching camera modes seems to work fine in the published game.

I can play fine and load new levels, as well as travel back and forth between levels.

The crash occurs only when I try to access the game menu. However, if I've exited the first level, and then try to access the game menu, it does not crash, but it does not load the game menu either.