Multiple users update information in a shared workbook. Sporadically, upon saving, Excel creates a new file with a name like "eb5fc200", which the user is unaware of. When they go back to add information, their latest data is not in the shared workbook, because it's in the odd new file. Sometimes I can open the new file with Excel, and sometimes I am asked to choose a program to open it with. The users all say they are not noticing anything different. Most of the time their updates are saved under the correct filename. Does anyone know what causes the new files to be created, and how to stop this from happening?