Hey there, I’m also having a similar problem with CS4 playing my AVCHD. I thought CS4 would be the end to all my problems, but apparently not. I got the MainConcept Plug-In for CS3 and there were choppiness. I thought that plug-in sucked, but apparently, it ran the video less choppier than CS4. I’m really out of ideas.
I’m running a AMD Phenom 9500 Quad-Core 2.2Ghz, nVidia GeForce 8500GT 512MB, 3.3GB of Ram, Vista Home Premium 32-Bit.
My currently theory is that my Local Disk C has like 20GB space left, and maybe Adobe requires MORE space inorder for it to run fine… though I’m not sure since I’m not all that technical.
My last great idea is to upgrade to a 64bit so it utilizes 4GB of my ram. If that doesn’t work… I’m going to go ballistic!