Can I undo a OS upgrade on a Mac? A couple of days ago, my iMac said software updates were available - did I want to install them. I opted to install them. Ever since then, the computer just randomly shuts off. I am running OS X 10.6.8 HELP!
If you don't have a time machine or other backup of your OS, then I think your only option is to reinstall 10.6 from DVD, download & install the 10.6.8 combo updater, & run software update up to, but not including, the most recent updates. This shouldn't lose any of your data - as long as you just install and without erasing - but a backup of your entire home folder before you start would be a Very Good Idea. (With 10.6, Apple has made Erase and Install harder to run accidentally, but it's possible for the determined....)