If you remove the memory card from the reader or external hard drive pulled from the USB port while Windows is reading or writing data, you can make the file gets corrupted, the disk is not readable, or both. The problem is not easy to know when Windows or an application that is reading or writing data. In fact, all seems quiet, but can a program is doing something. That is why to use the Safely Remove Hardware option (remove the hardware safely) - although it can be hidden and slightly confusing. The icon in the system tray, you can expand by clicking the arrow and you will see a pop-up menu lists the devices can be "removed safe ". Click on the icon corresponding to the memory card, flash drive ... to remove and wait until they appear the message "Safe to Remove Hardware". Then you can remove the device. If you do not see the Safely Remove Hardware icon in the system tray, or if you're not entirely sure of the icons in the list corresponding to your card or drive, your choices Others: Open Computer (or My Computer) and find the icon of the device. Right-click it and select Eject.