Well, if it doens`t work to boot demos that way, then try File->Run Elf, browse the CD for ELF files (files belonging to the demos, they are probably located in their rispective folder) and run them. This is like starting the demos directly without going to the menu.
And next time, please write in English so we can understand.
Try using SPU2null. Some games may crash when trying to produce sound. And make sure you`re not using scph10000 bios (japan bios), any other bios will do. If that doesn`t work, then it means that those games simply don`t run.