I'm new, so not sure if this thread is in the right place, please let me know if not. I'm hoping someone can shed some light on a problem I've had recently. It may be a long story... so here goes. I'm using an iMac purchased brand new just over 2 years ago. I'm a graphic designer, so mainly using Adobe Creative Cloud products. I woke up Tuesday morning to discover all my work had disappeared, the trash was empty and my whole desktop looked empty and different. I restarted and it came up with a screen asking me for my apple ID, like it had totally reset itself and I had just bought a new computer. Everything gone, all my settings for things, all my work. The only thing left was my apps, system, fonts etc. Luckily I had a time machine back up and retrieved most things. Although (silly me) didn't realise my time capsule wasn't big enough to store things so it had deleted anything old to make way for new. I've since bought a 3TB time capsule and ticked the box to alert me that it has deleted old items. I'm trying to move forward but have this niggly worry and concern (and curiosity!) as to why this happened! So a background to what was happening before everything disappeared... I updated to Yosemite about 5 days before. I think it restarted by itself, but I can't be sure. I'm not sure I had even shut my computer down after the install, as I was so busy at the time. The night before my mac did this I was working late and a window came up telling me my google drive was missing. I ignored it and thought I'd sort it another day. Then my drop box icon at the top of my screen disappeared. I use dropbox a lot for transferring work to clients so I tried to restart it by double clicking it in my app folder, but nothing happened so I went to the dropbox website and reinstalled it. It said it was updating the files (or something to that effect) and would take a while so I left it running and went to bed. When I got to bed, I remembered I was going to factory rest my iPod so I could clean it of my stuff and give it to my daughter, so I did that then. I have no idea if any of these things are related to what happened the next morning, but thought I'd put it out there, in case it did. I called apple support and they had no idea what could have happened, suggested I do a Verify Disk Permissions etc (which I did) and nothing enlightening came up. The disk was fine. Can anyone shed any light as to what might have happened? I'm confused, embarrassed and worried it could happen again.