Should you find that WMP art cache is the culprit I have just come across this piece of advice:-

"I found an easier way (although it took about 12 hours to finally delete almost 30gb of .jpg files!).

I use Piriform's 'Ccleaner' and there is an item in the cleaner list called 'Custom Files and Folders'. If you check the box next to that, then go to 'settings' and 'include' and add the "windows\serviceprofiles\networkservice\appdata\local\microsoft\media player\art cache\localmls" to the list.

I removed the checks from all the other boxes in the cleaner list, then ran it. As I say, it took 12 hours to delete it all - but at the end of it, that folder is finally empty! When it finally finished, I rechecked the other stuff I usually clear out.

Now the advantages of doing it that way are that ccleaner doesn't stop responding with the task, which explorer did on my machine. Plus the setting is now there - no batch file necessary. It will clear the folder every time I run it."

Forgot to mention that you may need to enable hidden files and folders if your Art cache appears "empty".

Control - type Folder Options, click on and go into View.