Sound error pop-up by Mp3tag v3.01

Not sure if last update had anything to do with the following problem:
I hit PLAY and an error message popa up and states...
"Canot open file "...bla bla.." for playing.
The operating system denied access to the specified file."
File can be played on other sound programs like MPC or Audacity.

If files cannot be opened for any odd purpose then it means that they are blocked by some other application - and this is an OS message and not one that MP3tag generates.
I cannot tell you why that file is blocked - this has always local reasons.
What happens if you close MP3tag and try to play the file?