All you Snow Leopard users, take heed: if you have the Guest account enabled, you’ll wanna remove it until Apple fixes the latest bug that’s been found, if you don’t want to lose your data. In a nutshell, what’s happening is that if you attempt to log into the Guest account, and the system hangs, it could lead to mass deletion of all user files on the primary account. That means everything. So you reboot to clear out the frozen system, log in to the main account, and files have vanished. Yeah, that’s pretty bad, and worse, Apple has yet to acknowledge it and issue any sort of statement to users on how to avoid this until they release a patch.

To be safe, we recommend simply disabling the Guest account on all your Macs that happen to be running Snow Leopard until a fix is released. Seriously, better safe than sorry.