ShockED seems to work fine now but when I try to open one of the original levels to edit them, it crashes for some reason. Here's what it shows:

Warning: failed to load script module "baseelev.osm"
Loaded script module "allobjs.osm"
Warning: failed to load script module "+xt :bunch of symbols: A.osm"
Warning: failed to load script module "traps.osm"
Warning: failed to load model "psishell" for obj -3414
Warning: failed to load model "psishell" for obj 1611

Would you recommend me reinstalling the game from scratch? Because it looks like something is wrong with my install.

Forget it. It was indeed a bad install. Reinstalling it fixed this.

Oh, and there was no descriptive error message in Shocked, it just made the Windows searching for solution screen pop up, followed by a pop up of how Windows can't find a solution. The usual.