You could try the 4.6 update for CS3 but I suspect the D300s may need a newer version of photoshop (I haven't got one here to try) if thats the case and you tried the 4.6 update then you'll have to download the free DNG converter from adobes website. That will convert your NEF files to DNG which is a sort of adobe raw, CS3 can open those ok.
It is another set in the workflow but it's easy and fairly quick.
I have just had this exact problem this evening, and I couldn't find a workable solution in Google.
I did fix it by doing this though:
Download this file:http://www.brothersoft.com/adobe-camera-raw-255281.html
Then unzip the camera raw file from it and open c:/program files (x86)/common files/adobe/plug-ins/CS3/File Formats/ and move the camera raw.8bi file that you find to a backup folder somewhere (just in case). Replace it with the downloaded one and start PS. That'll do it.
(p.s. if you're on 32-bit ignore the reference to "(x86)".
LMK if you cant get the file. i will pm u a direct link.
Often if you cannot open raw files a camera raw update is required. Search for 'adobe camera raw' you should be able to find the update fairly easily.
Beercan
Thanks, I downloaded and installed but Bridge and CS3 still do not recognise NEF
Is there anything on the Nikon site ?
cant remember what I had to do with my D90
Steve T, I had the same issue so in the end took the risk and completely deleted the camera raw.8bi file from the folder I mentioned, then replaced it.
Also, try this to sense-check:
In PS, go HELP>ABOUT PLUG-IN>CAMERA RAW and see what version comes up. Mine was saying 4.1 and after deleting the old file and putting the new one in, and restarting PS, it now says version 4.6.0.30
Well from what I have read I dont think Adobe have updated for CS3 which is a bit of a Bummer. I shall have to stick with DNG converter until Lightroom 4 comes out.
Its a shame not all camera manufacturers take Pentax's lead in having DNG as an on-board file option.