Apple has admitted that its latest operating system Snow Leopard harbours a bug that can accidentally delete data belonging to the computer’s owner.

The problem occurs when some users who upgraded to the Snow Leopard – which was released at the end of August – log into a “guest” account on their machines. When they log back in under their own name, all of the files in their home directory – such as documents, music and videos – have been deleted. One of the customer reports in the Apple discussion forum, “I had the guest account enabled on my MBP – I accidentally clicked on that when I went to log in. It took a few minutes to log in then after I had logged out of that account and back into mine my enter home directory had been wiped. All of doc, musics, etc gone.”

Another user raises two issues with the Snow Leopard — Home folder lost – user account restored to default. He states: 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.

The partition where my home folder lives is now virtually empty. I used stellar pheonix to try to recover the files from my home folder, but it did not find them as lost not as deleted files. It gave me the option of recovering about 40GB of deleted files, but they were legitimately deleted files.

Nice! Although I do have little sympathy for people who would apply a major upgrade without a backup.