Unable to play 1.6 on osx 10.5.8 using new launcher (Invalid memory access of location)

I just got the new launcher from Mojang.com and tried it.
First, the snapshot download was a bit slow (slower than downloading 1.5 with the old launcher). But then, when it had finished I got an error message in the new lawncher's development conslole that said:

Client> Invalid memory access of location 0x0 rip=0x0

I restarted the computer to clear RAM but still got the same errror.