I'm not sure of the solution, but for me it work.
The first time that I'm install MacOS X public beta, I format my MacOs X partition in UNIX format. Then classic not work.
After, I try to format my MacOs X partion in HFS+ and classic work without any problem.
For me it work, try if you can.
The first time that I'm install MacOS X public beta, I format my MacOs X partition in UNIX format. Then classic not work.
After, I try to format my MacOs X partion in HFS+ and classic work without any problem.
For me it work, try if you can.