According to Apple’s discussion board the cases of automatic deletion of the user’s data from the Mac running on Snow Leopard are increasing day by day. The Snow Leopard bugs are reported by the users especially when they login on their Macs through Guests user accounts or get upgrade to Snow Leopard updates and after that automatically they lost the data from their own account and even they lost the Home folder.

As one of the Mac bug report is following:

“I installed SL last weekend, no major problems but many annoying bugs. This morning when I woke up the computer had hung – screen saver was frozen. I held down the power key to shutdown. Turned the computer back on, clicked on my user account icon, and it was like I’d just picked up a new computer… my home folder had been replaced with a “straight out of the box” home folder. Standard desktop, standard dock, nothing in my documents folder, standard library. My entire home folder is gone.”

Right now Apple doesn’t speak any word on this issue, so the best solution is to take the backup before any upgrade or installation on Mac.