"I haz eat yur data!"
Several posts on the Apple Support forums (1, 2) dating back to 12 September indicate that some users have been losing all their data due to a nasty bug in Snow Leopard, a.k.a. Mac OS 10.6.
On Saturday iTWire reported on the bug which rears its head when a user logs into their Mac's Guest account and then tries to log back into their regular account.
In some cases, users have reported finding their regular account empty of data, as though it were a brand new account... The home directory still exists under "/Users/username" but is completely empty.
Affected users report that data is unrecoverable and cannot be found on the hard drive. The only way to recover is from a backup on external media. You do make regular backups, right?
Apple acknowledged the problem on Monday stating:
We are aware of the issue, which occurs only in extremely rare cases, and we are working on a fix," an Apple representative said in a prepared statement Monday.
CNet has posted a technique for restoring a lost home folder from a backup if you've been afflicted. A work around – until Apple releases a fix – is to disable the Guest account, or disable it and re-enable it as a native Snow Leopard account. It's highly recommended that you perform and maintain a complete and bootable backup.
Update: User "WalterDweller" on the Apple support forums claims that the bug may not be limited to Snow Leopard, saying "I had the same thing happen to me with Leopard 10.5... when I called Apple they said they had never heard of it happening before..."
Gratuitous Snow Leopard pic from Apple Scoop.