I've just built v.0.8.4 for OS-X 10.5.8 and get the following:
pyxplot> plot sin(x)
pyxplot(6066) malloc: *** error for object 0x5f313158: Non-aligned pointer being freed
*** set a breakpoint in malloc_error_break to debug
pyxplot(6066) malloc: *** error for object 0x676e6953: Non-aligned pointer being freed
etc....
Version 0.7.1 builds and runs with no problems. Any ideas? Thanks.