Try MagicIso. It works when others don't.
Seconding that and the trial version of MagicISO works just fine because the extracted image comes in under the trial version limitation.
I opened the image with Magic ISO, right clicked on it, selected extract, then after the files were extracted, I clicked on the installer ad a few minutes later got my butt handed to me by a Klingon frigate in Skirmish mode. Aaaagghh I am REALLY rusty.
Anyhow, hope it works for you!