Windows can't stop your 'Generic volume' device because a program is still using it. Close any programs that might be using the device, and then try again later

My system is Windows 7 Home Premium 64-bit.  I have a 2.8 GHz Intel Core i7-860 processor and 8 GB of RAM.  When I try to safely eject my Western Digital Elements external hard drive I get the error "Windows can't stop your 'Generic volume' device because a program is still using it. Close any programs that might be using the device, and then try again later."  Waiting around for it doesn't work.  I've tried closing absolutely everthing out including Windows Explorer--that doesn't work.  I've used task manager to kill all the processes and stop services that might be using the external drive in some way--that doesn't seem to work either.  But there are so many processes and services and it's hard to tell which ones might be preventing the drive from being ejected.  I tried to kill all those that  say Western Digital.  I tried to kill the explorer.exe process too.  None of this works.  I realize that I can just shut down my computer but I want to be able to safely remove the external drive without having to shut down. I also tried a program called EjectUSB and that didn't work either.  I tried logging out and logging back in. No dice there either. I think I've tried just about everything.  I've googled everywhere and can't find a solution.  Anybody have any other ideas?