martyredwhitman: Well, after changing the DEP, and replacing the
sound 
graphics card with a GeForce 7900 GT/OC, still no difference.
Sorry if I've missed something in the thread, but isn't a GF 7900 a five year-old GPU? The core clock speed is rather high, but the 256 MB memory is a bit low for display of heavy AVCHD stuff. Is there a reason you picked the GF7900 instead of a 2011-vintage card? If you got it for free from a friend, or scavenged it from some throwaway, don't complain. But, if you paid any money, you might consider exchanging it for something properly vetted for the latest video stuff, which would include AVCHD-2 (the 28mbps 1920x1080 50p/60p stuff) or possibly even 4k video (which may start to appear in some prosumer cameras late next year). Don't be too cheap, unless you enjoy crashes, hangs, black screens, or unending trouble. But if stinginess is supreme, first try editing with a trial version of another product. If they work, fine, but if your stingy gene throws a fit when you see the cost of the full versions, maybe you'll want to test another graphics card.