To fix this problem, try to re-download the launcher, because the new launcher is different from the old, and the old Minecraft can not use the new launcher. I fixed this problem this way: I copied all the files from the .minecraft folder to another folder (i.e. did backup.). Then through the launcher I downloaded and launched Minecraft 1.5.2! Good luck! 🙂
Evgenii Gerashenko
To fix this problem, try to re-download the launcher, because the new launcher is different from the old, and the old Minecraft can not use the new launcher. I fixed this problem this way: I copied all the files from the .minecraft folder to another folder (i.e. did backup.). Then through the launcher I downloaded and launched Minecraft 1.5.2! Good luck! 🙂