Haven't really had much problems... except with AC adapters for GameBoys and their spawn. Not Car adapters, just AC adapters.
Ok, they work for a while, you aren't complaining. After the warrenty is over, they must be rigged or something to give people problems. Most of my AC adapters wont give power to my GBs unless they are turned at just the right angle... and then sometimes they still don't work.
AC adapters are a communist plot. I'll stick to my rechargable batteries, thanks.