This happens in a computer lab environment, has happened at least 3 times. We are running Microsoft Office 2008 for mac on Leopard, everything is updated. Our user's home directories are on a network drive, but the /Library/Cache folder is running locally.
Typically a student will have a Word file that they have been working on, it's been saved before they even logged onto the computer that day. They log on, open the document, click the save icon (not go to File > Save), sometimes even save multiple times, then close Word. The document is now gone.
It's not hidden, there are no autosaves or anything in the Cache folder. Definitely not in the trash or trashes folder. It can't find it when you click on it in 'recent documents'. Searching meticulously though every folder in their home drive turns up nothing. They look using Finder, I look ssh'd as root into their home using ls -la. I look for similar files in case they renamed it by mistake. It's gone. Disappeared. Vaporized.
It's happened to at least 3 different users in the past year. Much whining.