Since Mac OS X 10.6 launched in late August, numerous reports online have detailed the issue, which is triggered by logging in and out of a guest account on a Snow Leopard machine. Upon logging back in to their regular account, users will find that it has been wiped of all data.
The issue has prompted numerous threads (1, 2, 3, 4, 5) on the Apple Support Discussions, with reports suggesting the issue cannot be reproduced with any exact certainty. Apple has yet to publicly acknowledge the issue.
"When I logged into my MacBook Pro this morning, it was as if I had logged into my Guest Account and not my standard user profile," user parshallnet said. "No icons on the desktop, the desktop wallpaper was the default 'space' photo and not the one I had assigned, no documents in the docs folder, apps behaved as if I'd never opened them before."
The issue was initially reported when Snow Leopard first launched, but complaints have grown as adoption of the platform has continued. Monday, Engadget highlighted the issue.
A month ago, CNet detailed a potential fix for the issue, which is reportedly caused when users have had a guest account enabled for login prior to the install of Snow Leopard. The easiest way to avoid the issue is disabling the guest account.
If afflicted by the bug, the home folder can be restored, though without a backup, the loss of data is likely permanent. If a user has Time Machine running, they can restore their Snow Leopard installation while holding 'C' at startup and choosing "Restore from Backup" from the "Utilities" menu.
Update: In a brief statement, Apple acknowledged the issue Monday evening, according to CNet
"We are aware of the issue, which occurs only in extremely rare cases, and we are working on a fix," a spokesperson said in a prepared statement.
Since its launch in August, Snow Leopard has been received with positive reviews and strong sales. A quick update, Mac OS X 10.6.1, was released soon after, but apparently did not provide relief from the guest account bug.
Mac OS X 10.6.2 is currently in beta and only available to developers. It has nearly 150 general focus areas.