Thanks so much for the response greatly appreciated!
Yes audio is 16 bit – though have since played around with other possibilities – nothing is playing continuously now.Have used Mp3, AVi files etc. Have changed location of source files so beleive this has ruled out possiblity of communication problems with program and ext. HDs. Have re-insalled program and also installed different copy – no use. So think it may be problem with my computer/system.
Will investigate new virus and spyware. Fingers crossed.
Many thanks
Malika