The bug reportedly affects only 64-bit platforms. Perhaps some part of the OS X boot process naively iterates from time stamps starting from 1970 up through "now", and treats 1969-12-31 UTC as a very large (perhaps unsigned) time stamp. On a 32-bit platform there are only 4 billion time stamps or so, so even a naive approach could work in a reasonable amount of time; a 64-bit platform, though, would have about 4 billion times more work to do, and users understandably don't want to wait that long. If we were designing POSIX from scratch, perhaps we could let (time_t)0 denote the Big Bang. Then, iPhone users would need to set the date to ~13,798,000,000 BCE to expose the bug. Nobody would have the patience to do that, since the UI forces them to scroll back year-by-year to the desired date. Problem solved!