Umm, under OS 3.9 (you have at least BoingBag1+2?) ... well, LOL, even under OS3.1. When upgrading to the buggy first OS3.5.. *I am the ONLY person to have it, I bet, LOL!* I went into HDTools, and set another partition as bootable, gave it a little lower priority than my normal boot drive, and could select between the 2 from Early Startup menu.. easy-peasy.... this type of thing won't mess up any data... even the clunky HDToolbox alerts you before any possibly bad changes....