Check disk space usage.
From the developer, “Every hard disk is too small if you just wait long enough. TreeSize Free tells you where precious space has gone to. TreeSize Free can be started from the context menu of a folder or drive and shows you the size of this folder, including its subfolders. Each folder can be expanded in Explorer-like style to see the size of its subfolders. Scanning is done in a thread, so you can already see results while TreeSize is working. The space, which is wasted by the file system can be displayed and the results can be printed in a report.”