So... I've been away from the modding scene for nearly a year, and... I accidentally deleted my old MEK files when cleaning my hard drive. I don't quite remember what location I should install it in, whether it should be in the same directory as my Custom Edition or in another location. I just can't remember what I'm supposed to do. Um... any help at all would be appreciated.

If you haven't figured it out already, just install the MEK wherever.

Sorry about that. I... had a brain fart. If I don't do something for a long time, I tend to forget how to do it. Anyway, I actually started remembering things after finding and reading a copy the README that survived in the My Documents folder of my computer. Sorry to bother everyone. I'm actually planning on revising my Campaign in either a 1.5 version that makes a few tweaks to some of the weapons and enemies for proper game-play balance (like removing the assault rifle's headshot capability), or a 2.0 version that has further changes.

I'm also going to probably release my five completed Halo: De-Evolved maps for everyone at some point. De-Evolved is basically where I replace all of the UNSC weapons with modern Earth military weapons. But after reaching level c20, I found it impossible to handle the Flood without spawning them with UNSC weapons, because those files are necessary for the map to compile and load and... honestly, it was difficult enough with my first campaign mod to alter the Flood to use the additional weapons I added, so I'm basically throwing in the towel on that mod.

I'm assuming you used the stock scripts, correct?

Ctrl+F and look for "weapons\assault rifle\assault rifle" through the scripts. You're looking for a global object_definition that references the weapons. There's probably more than just the assault rifle. You should change the tagpath to reference the new weapons that you added in, the most applicable replacement.

I don't KNOW that this was the issue, however what I'm assuming is happening is the weapons that are referenced for the cutscenes (putting the assault rifle into the master chief's hand) is what's causing your issue.

Otherwise, I can easily help you with ensuring all the tags are replaced properly and all A.I. are using the weapons they're supposed to. Hate to see a project lost to something that might be minor