Sorry, an incorrect project option got merged from the main CVS branch into the 0.12.1 release by mistake under VC6 (VC7 and gcc users are unaffected); if you have already downloaded the release and get an error about missing file ‘OgrePrecompiledHeaders.cpp’, then please download the fixed OgreMain project file and save it in ogrenew/OgreMain/scripts.
I’m fixing the download archive now so future downloaders won’t get this problem.