If your video preview window is not working, make sure you have not accidentally select to view the preview on "External Monitor" or have an FX placed on the preview window. To ensure it is nothing of this nature, close out of the program. Before restarting the application, hold down the Shift+Ctrl key. While holding down these keys, double click the Icon for the application. Drag an item to the timeline. Are you now able to properly preview video?

Thanks for your contributions. Neither has solved the problems. I have loaded .avi clips from a pre captured project and placed on timeline – the first clip appears in preview window. When I try to play on the timeline a message comes
“An error occurred while starting playback.
An invalid device was specified.”
If I press for “Details” I get
“The playback device does not support the current output format”.
If I try to change the project properties I get
“One or more audio playback devices do not support the current sample rate and/or bit depth”
“An invalid device was specified”
“Details” once again gives me
“does not support 44,100Hz at 16 bits.
Preview Port () does not support 44,100Hz at 16 bits”
Despite all this I can render the clips to “Make Movie” which will play on Windows Movie Maker complete with sound!

I have tried adjusting audio and voice rates in Control Settings with no success.
My system is Athlon 800 processor with Windows ME, plenty of storage, 512mb RAM, on board sound –
VIA AC ’97 Audio Controller (WDM). There is a long list of CODECs – do I need to change their priority?
I am using downloaded Videofactory 2.0c (Build 125)
Keith H