I needed to create a (local) project comprising one Word and one PowerPoint file but got the error message

"The process cannot access the file xxx because it is being used by another process"

for the Powerpoint file. The file wasn't obviously already in use.

I did manage to process the file by creating a project with just the Word file, then adding the pptx to the existing project! But that shouldn't be necessary...

Any thoughts as to what's going on here?

Just to check the problem wasn't inherent to that specific pptx I tried the process with a PowerPoint from an entirely different source... same result.