swa66 - 9:24 pm on Feb 19, 2013 (gmt 0)
IE 5.23 is a mac version, actually the last MSFT ever distributed - it's a piece of utter junk IMHO.
It's compiled for the PowerPC architecture, so you need an emulator like rosetta to run it on modern mac hardware. Rosetta itself was discontinued as well (not installed by default under snow leopard (10.6), not supported anymore on Lion (10.7) and Mountain Lion (10.8)) Rosetta was a way to facilitate the transition of the PowerPC architecture to the Intel based one for Tiger (10.4) and Leopard (10.5) - a rather painless transition to those who used rosetta (even unknowingly sometimes).
If anybody wants it: archive.org has a copy of IE 5.23. But seriously: forget about it. This IE is much, much worse than any other IE version you might ever run into. It had it's very own special set of IE bugs ("features" as MSFT only fixed security bugs or legal problems in IE.)