I've now d/l'ed "Safari 5.1" numerous times, and if the SHA1 test is meaningful in this instance, almost all of my d/l's have been the correct version.
Is it possible that a small number, possibly just one, of Apple's servers somehow weren't update to v 5.1?
The new Great Equalizer is the SEND button.
In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire