Every so often Solidworks gets the erroneous notion that a part is read-only. When I try to edit it, I get the warning that I'm messing with a read-only part, and when I try to save it I can only save-as. I can save it with the original name, but I get the usual "this part already exists, do you want to replace it" warning.

This just happened with a brand new part! It has never been checked into PDM. Nobody but me has ever seen it. Why does this happen, and how can I twist SW's arm to recognize the truth?

Very annoying.