Windows doesn't always allow you to safely remove a flash drive or external hard drive. Klaatu asked theAnswer Lineforum for advice.
If you simply pull an external drive out of a running computer, you're asking for trouble. You might lose files, crash applications, or even ruin everything on the computer. But removing it safely isn't always as easy as it should be.
Windows' built-in solution usually works: Click the Safely Remove Hardware icon in the notification area (aka the system tray or the systray) and select the drive. When you get the "Safe To Remove Hardware" message, it's safe to remove the hardware.
But sometimes, "usually" isn't good enough, and Windows instead tells you that "This device is currently in use."
But Windows won't tell you what's using the device. Without that information, it's tough to know how to fix the problem.
Guessing makes a good start. Close all of your Windows Explorer windows, along with any programs that might be holding onto a file from the drive. Then try the Safely Remove Hardware icon again.
If that doesn't work, you can simply shut down your computer--not hibernate it or put it in sleep mode--but shut it down completely. That always works, but it takes time and interrupts your workflow.
In the original forum discussion, Flashorn offered an improved variation: Log off, log on, and try again. It's faster than a full shutdown and reboot, and it will probably close whatever process is causing the problem. But it still takes time.
Which is why I prefer Unlocker. Intended to help you free up files that Windows won't let you delete, it can also help free external drives. Unlocker doesn't cost anything, although you're encouraged to make a $5 donation.
Download and install the program. Then, the next time Windows tells you that a "device is currently in use," right-click the drive and select Unlocker. The program will tell you what process or processes are causing the problem.
It will also offer solutions. It can kill the process(es), but that can make Windows unstable. It can also try to unlock the files from one or all processes without killing them.
My favorite solution isn't on the Unlocker menu. Once you know what process is causing the problem, you can usually figure out what application you need to close--they generally have the same name. So you just close that program manually, saving all appropriate files, then use the Safely Remove Hardware icon again.