Hey, thanks for getting back to me. I moved the entire folder to the root drive and I'm still getting the same issue.
I deleted HERETIC.wad from the "C:\Hakros Doom Launcher 1.6\data\games" folder and from the "C:\Hakros Doom Launcher 1.6\data\engines\gzdoom 4.5.0" folder (where it gets copied over from the games folder). Is the WAD file actually supposed to run from the gzdoom folder? None of the other IWADs make a copy in any of the engine folders or give me an error. Sorry to keep bothering you with this. It's just weird and I wanted to figure out why it just happens with Heretic.