Nero vision 4 problem

I am using vision 4 to capture videos from a vcr. I am having two problems I cant seem to figure out. The first problem is preview video and video showing while its being captured does a hesitating thing once I turn the audio on. In other words when I open the program the little preview scrren is showing whatever the vcr is showing no problem. I have to go and select my audio device to make sure I get the audio and when I do that the picture does this thing where it plays then stops for about a second then plays again. It does this after I hit the capture button as well . But once the capture is done and i go back to preview it it plays ok but the picture quality isn’t very good. The second problem is with this happening it takes forever to capture a single VHS. Is a program clitch or am I doing something wrong?