One of my pet peeves is how a lot of advice about GM's burnout is actually about GM's block (akin to writer's block). This bugs me because they are very different kettle of fish and because I've been somewhat burnt out for several months now and the absence of solid advice on how to counteract it. I've trawled through dozens of advice articles and web-sites and most of them talk about ways to boost creativity. My creative stores are just fine, thank you. I'm quite happy to write articles, world build and create adventure paths. In fact, during my period of burnout, I've actually written and edited about 80 pages of player information (not all for the same players, mind, about 10 pages per covenant, 2 per clan, 20 of general information, which can be perused or ignored at the player's whim). My problem is that I'm starting to loathe my GM time.
So let's look at GM's Block.
Your ideas become stagnant and stale. In fact, just generating new ideas seems like hard work because you lack inspiration. Your players start to comment on how they'd like to see a little enrichment in their game. They're starting to get a bit bored and you probably are too but you just can't think of anything new and interesting to keep everyone going. In this case, watching movies, dipping briefly into a new genre one-shot, or letting someone else run a few sessions so you can start champing at the bit again are all good things. Heck, I've even gotten inspired by attending concerts by musicians I didn't even like!
Now let's look at GM Burnout.
1) Exhaustion. Simply thinking about running a game leaves you exhausted. The mental resources required to comprehend an upcoming session makes you want to go and lie down. You look at the game preparation and/or actual session time as a dreaded chore that will soon be over. Hopefully. When the players are distractable at the start of the game, you sit back and let them talk, chat, ruminate.... You let the OOC Chit-Chat time drag on and on and on as every minute of reduced play-time is a minute won.
2) Cynicism. Your players suck. Things will never get any better. You have to learn to live with all those irritations that any player brings to the table and (see Point 1), it really doesn't seem worth it to you. Why are you putting in all this effort for so little reward? You must be a real sucker for punishment. What did the players ever do to earn your slavish devotion? Why isn't anyone slavishly devoting hours and hours and hours to your enjoyment? You know you can't / shouldn't expect a player to put in thirty minutes a week for the game without being a slave driver. They expect hours from you! It's so unfair.
3) Sense of Inefficiency. You suck. You lack the skills to make things work. Maybe it's all your fault, anyway. You've rewarded poor behaviours. You've punished good ones. Or something. If you were a better Storyteller, all those things that bug you would cease and you could just get on with it.
Obviously people vary on where they sit on this burnout scale but, as you can see, it's more hard-core and pervasive than a simple lack of creativity. Simply taking a holiday might not help, either, at least not in the short-term. If your last few months of roleplaying was a painful waste of time then it makes sense that having a few weeks break from it won't necessarily help. Even a few months won't necessarily put enough distance between you and the bad memories. Because, regardless of how good the game actually is to an outside perspective, it doesn't feel good to you. It feels horrible. Besides which, if you go back to doing exactly what caused you the pain in the first place you will probably suffer from it again. Doing the same thing over and over and expecting different outcomes is a silly thing indeed.
The wikipedia entry on it has some interesting details on it, particularly the way it develops. It also gives players and Game Masters ideas on how to arrest the progression of symptoms ... or at least reduce the causes and therefore the progression.