The 3D screensavers fail every time, dumping core. I haven't looked into why but probably floating point failures. It seems every screensaver that uses Mesa has this problem.
*All* of them? Crap. Last I checked it was only about half of them. :( (FWIW, the same sorts of problems happen on ia64; probably a general 64-bit issue.)
*** This bug has been marked as a duplicate of 11115 ***