What model of nikon camera are the camera raw files from?
Which operating system are you using?
I'm using a D90 and D5100, both of which are on the compatible list for the latest Camera Raw update. The computer is running on Windows 7.
Raw files from the D90 require Camera Raw 5.1 which is definitely compatible with CS4 provided the Camera Raw plug-in has been upgraded.
However, Raw files from the D5100 were first supported in Camera Raw 6.4 which is only compatible with CS5 and later. So you'll never be able to open Raw D5100 files in CS4 since there is no CS4-compatible plug-in which supports that camera model.
You can download the free Adobe DNG converter, convert all D5100 Raw files to DNG format then edit the DNGs in CS4
I'll give that a try. Thanks very much, John.