I recently posted a message about my final DVD rendering not having any sound (and sometimes - I didn't mention this - the video is just a green background WITH sound), even though the 'preview' of the DVD works perfectly. I think I've found the cause:
My system has two monitors, which is very handy for video editing because you can use one of the monitors for full screen preview while using the other one for the timeline, etc. But, I got to thinking that perhaps that other screen is using up too much video memory. If I'm not mistaken, the GPU accelerator to help speed up rendering and some effects, etc, needs to run in the video card's own memory. With 'only' 1GB of video memory to start with and two screens to take care of, there just wasn't enough available video memory to hold all of the data needed for the GPU to do its thing. I disconnected my second monitor and the problem went away.
If this IS the problem, I'd like to make a suggestion to Cyberlink. If the GPU accelerator program reports that there is not enough video memory to do its thing, please notify the user so that they can take steps to fix the situation such as disconnecting the secondary monitor like I did, or upgrading their video card to one with more memory and/or more powerful chipset, etc.
Russell1967 System specs: Windows 7 Professional x64; Gigabyte Z77-DS3H motherboard with i5-3579K 3.8Ghz processor with 32GB RAM; Zotac GTX 760 w/4GB; 1xWestern Digital 1TB 10,000RPM HD; 1x Samsung 840 Pro SSD System Drive