Christian I hope that you are sorted. But I had a similar problem. Every time I selected a n avi file windows explorer said it had a problem and closed down.The problem turned out to be a change of settings in media player. When
I checked the settings it had a tick in automatically get
licence for protected files. Of course all videos and dvd’s are protected, once I removed the tick the job was done,
As for files not deleting go to downloads.com and download the free program dr delete click the browse button and select the file you will have to select each file and click delete then reboot the folder will be empty after the reboot and you can then right click and delete the empty folder
