My computer was new in December last year, and came with Windows 7. While it is very fast to start up and most things seem great with it compared with say, my computer at work, it seems kind of unstable. Every few times I start it up, it will start Windows and be okay, then a few minutes I'll be faced with a Blue Screen of Death and a few choice swear words. Usually, once I start WoW up it's fine and I can play for hours with no problems, so it doesn't worry me that much usually.
Until last night. I finished playing on Thursday night and logged out for the night, but as I was exiting the game, I got a BSOD. I thought nothing of it and just shut the box down, but when I started WoW up on Friday evening, I logged in my Druid and realised something was very, very wrong. I had lost all of my addon settings. All. Of. Them.
My macros were gone. My power auras. My painfully configured pitbull, grid and clique setups.
It took me two and a half hours to put it back together, then I limped through a heroic to make sure everythng was okay. I thanked whichever deity you like that I had put my macros and power aura setups into blog posts, because I was easily able to import and recreate them again.
I logged onto Aefa to see if her settings were kaput as well - I hadn't exported her power auras and wasn't looking forward to having to set them up again, but it seems that since I was logging off Leesah at the time, it was only her addon variables that were corrupted. Aefa's specific macros and power auras were fine and intact, and it was only the shared settings like pitbull and bartender that were broken.
The moral of the story - Back Up Your WTF Folder!
This is the folder that contains all the addon settings for each of your characters. If something goes wrong while you're exiting the game, these files could be corrupted and you'll have to go through the annoyance of setting up your UI again.