It is very easy to accidentally drag and drop items into a new location without realizing it (i.e. an e-mail folder in Outlook). If you turn on the ‘ClickLock’ feature on your mouse it can help eliminate any accidental errors. When ‘ClickLock’ is on, you have to click a second time to drop the item in its new location. ‘ClickLock’ settings are different in Windows XP and Windows 7, see the appropriate documentation and video for your operating system.