Looks to me like PS is opening the files in AdobeRGB colorspace, that'd do it
The question is if LR's adjustments are handed over to PS?
Normally I would expect some dialog asking you if you want to render with LR adjustments or not. Maybe you have switched off those dialogs?
Then it might be a question of matching ACR-versions between Lightroom and Photoshop:
I am not familiar with CS4, but LR3 matches with CS5 (i.e. ACR 6.x), LR4 with CS6 (i.e. ACR 7.x. or 6.7 of CS5)
So it could be that your CS4 does not know the ACR-version used by LR3, hence can only open without LR3's develop settings.
CS4 matched with LR2.
If you need to stick with CS4, you may need to switch the dialogs back on and let LR3 render a TIFF for hand-over to CS4.
Should you dislike that, upgrade Photoshop... but then maybe to really current versions, so LR4-CS6 ?
Nope I am in sRGB.....
It has been very confusing because I can get an image to open normally in CS4 by resetting ALL the settings.... i wrote down the settings, re-set, made sure it opened with the correct color rendition/not desaturated (for lack of a better term.....), and then went through and "re-created" the image step by step, starting with white balance and on down, and opening it in CS4 every step, to see what was making the color render that way in CS4. I think I have narrowed it down to the Nikon V4 camera profiles... because if I set my camera profile to "d2x mode1 v2" it opens normally (with all of my other lightroom edits made...) but if i simply switch to "d2x mode 1 v4" it will desaturate upon opening in cs4.
I've also had troubles like this from time to time in the past, and thought it had something to do with the adjustment brush.
Has anyone encountered this problem before?? Is it a compatibility issue with CS4 being an older version of photoshop?