Windows Vista action cannot be completed because the folder is open in another program

I got a good one, I just backed up all my pictures to an outside drive and I found one folder that I thought was empty. When I try to delete it I get this "action cannot be completed because the folder is open in another program ", vista will not let me delete it. Any suggestions? I've tried everything, even shutting down explorer and other processes. What gives?

 

What's the name of the folder?

 

Thanks, reboot worked. I guess my movie maker had a hold on the folder somehow. Thanks..