Play Audio command doesn't work in DOpus 10 & 11

Hi all, this is a first post, so forgive if too wordy. Have been a devoted DOpus user since the earliest
Amiga versions (1986?) and am still doing all file management through DOpus 11.7 64-bit on Windows 8.1 64-bit,
on a decent fast machine. A main pre-Xmas activity is compiling Audio CDs for number of music-mad nieces & nephews.
Problem: Double-clicking on a wav file in the lister usually launches the internal player, which starts playing without further input.
However, with DOpus 10, 10.5, and current 11.7 versions although player appears it seems frozen - no movement of
tab on progress bar, no sound. Hitting controls has no effect. I should add other music players perform normally
eg Alt-double-click on wav song in the lister launches Windows Media Player. Any ideas? Is there a better way to do
this with a third-party player? Thanks

The standard WAV codec/splitter has probably been taken over or had its registry settings broken by something (e.g. a codec pack). You can usually repair it by following the first part of HOW TO: Enable/fix playback of various media formats in Opus.