Snow Leopard Bug Could Leave You with no User Data
Operating system bugs can often have undesirable consequences. The possibility of losing all of your user data is pretty high up on the list of things you would rather didn't happen, but that is what some users have been reporting after upgrading to Snow Leopard, the latest version of Apple's Mac OS X. The problem has been cropping up when users, intentionally or accidentally, have logged into the 'guest' account. After logging out of this account and back into a normal one, they have found settings have been reset and all of the user data wiped along with it, leaving an empty directory under "Users/username". Even worse, it appears that there is no easy way to recover the lost data, with users having to resort to external backups (assuming they have them).
At the moment, disabling the guest account is a possible workaround for the problem. Anyone who had the guest account enabled when upgrading from Leopard to Snow Leopard could potentially be affected. Apple has now confirmed it knows about the problem, which says only occurs in extreme cases, and that it is working on a fix.