The video clips are Standard Definition MP4 with AAC audio @ 24Khz, 128Kbps, Stereo.
I also found that clips produced by PD8 in the MP4 format with stereo sound are AAC audio @ 44Khz, 125Kbps, stereo, and these files also do not display the Audio Waveform.
Processed clips with mpg or m2ts extensions use a different audio format and appear as normal.
As I have the original program retail version 1930 on CD, I uninstalled PD8 2508, and then deleted the registry entries and also used the microsoft cleanup tool as per forum instructions.
Upon reinstalling my original 1930 version I find I have now created the same problem in version 1930.
This seems to suggest that certain dll or other referenced files are being altered by the program during the update but not reverted back to the previous versions when the program is uninstalled.
Normally other programs give options during an uninstall and list which resident files have been altered/updated and give a choice as to what action to take.
As most of the contributers to this forum seem to have HiDef camcorders which I don't think use this audio format, I don't expect others to have experienced this problem.
I have lodged a ticket with cyberlink, so will see what they say.
PatC