In one sentence, describe what the following article is about:

The most common cause of this error message is a program currently accessing the file you are trying to delete. For example, if you are trying to delete a document that is currently open in Word, or trying to delete a song that is currently playing. " Press Ctrl+Alt+Del and select "Task Manager" from the menu. Click on the "User Name" tab and find the entries under your username. Most of these programs can be ended without causing the system to crash. You can do this by selecting them and clicking "End Process." If you close a program that causes the system to become unstable, restart your computer to restore. Oftentimes, restarting your computer will release the hold that a program had on a specific file. Try deleting the file after you have completed the restart and before you open any other programs. If the file still shows the error message, continue on to the next method.

Summary:
Close any open programs. Open the "Task Manager. Close the programs you recognize. Restart your computer.