So, I'm having some issues with terror missions.

[Son_of_Orion]

I'm not sure whether I should post this here or the bug tracker, since I can't seem to find anyone else with the problem. Maybe it's something I did, I'm not sure. Anyway, on terror missions, there are certain buildings where my troops can just phase and shoot through walls like they were nothing. Also, certain single-block doors won't open, and I can't climb ladders. The only modifications I made to the game were changing the music and sound effects, as well as adding new soldier names. I posted the save file down below. Have fun phasing through walls!

[SHADO]

It looks & sounds like you may have/had the Dawn City mod mixed into your install.  I'd reinstall the data set (particularly the Maps, Terrain & Routes dirs) from a clean (un-modded) source & try again (i.e., start a new terror mission).

[darkestaxe]

... and I can't climb ladders. The only modifications I made to the game were changing the music and sound effects, as well as adding new soldier names.

There's no ladders in vanilla x-com, I didn't even know there was a climbable ladder mod.