Is that a single core or dual core processor?

And are you editing standard definition or high definition video?

The symptoms you describe are typical of trying to edit HDV or AVCHD video with a processor that is not fast enough.

I also encountered this when Pinnacle rewrote Studio 10 around the Liquid Edition "engine". My single core hyperthreaded processor which could handle Studio 9 just fine began doing what you described with Studio 10 and in addition to slow and out of synch editing window, also took forever to do simple background rendering.

I encountered what you describe again 2 days ago trying a test edit on 1920x1080 17Mbps AVCHD files on a laptop with Intel T7250 dual core 2.0GHz processor. 1440x1080 at 12Mbps can be edited on that computer OK but I shot the project at the camera's highest resolution.