After loading a file and pressing the Play icon I get all the time a message together with a popup:

Unable to use midi output driver (beginning of message)

Output driver is installed properly but is currently in use by another program (first text line in popup)

I already followed up the tip: http://www.pgmusic.com/techfaq17.htm#80 and unchecked all sw synths and configured the Roland VSG DXI synth, but it has the same result.

After pressing the cancel button in the popup, the replay starts normally.

Please help