Right click drag drop not working
Bizarrely, I came across this post:
Which suggests holding down right click and pressing esc.
I thought it was a joke at first, as I've never heard of that short cut.
It worked.
Assuming you do not have damaged DLL's (I did not), the fix is ridiculously simple... hit the ESC key twice. I'm not sure how it get's "disabled" but this has happened to me twice, and both times, hitting ESC twice (quickly) returns the right click drag and drop back to normal.
Hope this helps.