Three nights ago, I was playing Platinum to procrastinate a big biology project due the next day. I got heaps and heaps of training done (catching several Pokemon and getting them from about level 6 to level 18). After I finally finished my project, I put the DS in sleep mode and promptly went to bed.
The next day when I came home from school, I started playing Platinum from where I had left off, but got into bed while playing because I was so tired from staying up all night on the project. I got into bed at 2:45. I woke up at 9:00 pm, and immediately jumped up and looked for my DS. It was sitting right there on the bed where I had been playing it hours earlier...face open. With the battery and almost four hours of play time dead. I wanted to cry and throw my DS into the wall.
Erm...but no, I've never given up on a game for that.
P.S.: A very similar thing happened to me playing Ruby version, where I had been playing all day, but then my GBA (the original) fell off my bed and the batteries fell out. I obviously don't save enough, lol.