After some thought I've come to the conclusion that the main reason I had as much trouble with the game on Friday as I did was that I didn't really want to be running that campaign in the first place. I was just doing it because I felt like I should. That's a lousy reason to be running a game, and it leads to lousy, short-shrift DMing. So I'm taking another break.
Not 100% sure when that's going to end. Or if it will. The last three games I've run have been frustrating, painful, and ended before they were intended to. I'm pretty happy with the gaming I'm already doing, and as long as that continues, I'm not sure running my own would be worth the potential for more frustration.
Now, that hasn't stopped me from starting to fiddle with a setting for a new campaign -- or rather, another campaign, since the planning for this one significantly predates the game I was running this semester. But I'm not entirely sure that this one will ever get run, and if it does, it will at least be very, very different from the kinds of games I've been trying to run. The "next game," if there is one, will almost certainly be online, via text chat, and it's only slightly less likely to be a solo game. It's probably going to be a system of my own invention, and it won't have many, if any, dungeons in it.
For now, though, I'm content to scribble. I'm also planning on doing more of a number of things that, lately, I've been thinking I'd much rather spend my time on than running the tabletop game. I've got a couple of fantasy novels to read, some drawing to do, and Settlers of Catan and Texas Hold 'Em to play, never mind the "regular" socializing that I'm finally starting to get the hang of. I'm going to do my best not to obsessively analyze and try to figure out "why" the games haven't been working. If an interesting setting comes out of my scribblings, I'll run another game. If not, I'll keep playing in the two games I'm already in, and find some other ways to occupy my time.