Demon wall graphics issue

I've been playing on a different computer and I noticed I can't see the purple ooze on the floor that he makes. I also noticed on this computer I can't see the firebombs that are shot out by the boss in Cape Westwind.

Anyone have any ideas what is causing this specific issue?

Some VGA issue. Happened to me a lot, so sad that there's no community reps addressing this. Try reinstalling your VGA driver and it should work okay. Or set it's settings to default.