Hi Vince,
when I just purchased my Sony standalone DVD-player, I got the same problem. Although it had a DivX/Xvid lable on it, is was unable to play any of my .avi files. I also got a "no codec" error message. I checked the Sony website and found a firmware upgrade for my DVD player to improve playback of .avi files. Since then it plays any file that I put in it.
Therefore I suggest you check the websites from Philips and Samsung and look for the latest firmware revision for your drive(s).
good luck!