I recently got a theme (Mire v2) that uses xPaintClass, and downloaded the module an put it in the modules folder. After a bit, I learned that that's not the right place, and put it right in my LiteStep directory. However, upon refreshing, I get a "Could not find initModuleEx()" error about xPaintClass, even though the theme I've reverted to (original Mire) doesn't use that module. What's going on?

Kill litestep and restart it and see if that helps.
Ctrl+Alt+F1 to kill
Then use the task manager to start litestep.exe again

Nope, didn't happen. However, I think I managed to fix my problems. Thanks anyway.