Do you have a repeatable, reproducible case? e.g., a specific file where the adjustments don't get saved?
No, unfortunately, I can't reproduce the problem. It occurs ramdonly. I can work on a file and open it in PS and then reopen the file in ACR and the adjustments are default. I can work on the file again, open in PS and reopen in ACR and the second time the adjustments are saved. I'm running OS 10.5.8 and scheduled for an upgrade to Lion, soon. Will that solve the problem?
This doesn't sound like an OS problem. So I don't think upgrading to Lion will change anything with regards to this.
That said, I'm a little confused by your steps. You say you open the file in Ps, then re-open the file in ACR. Which file are you opening? If you open a raw file into Ps, this creates a new unsaved document. If you save that new document and open that in ACR, the adjustments are already "baked in" by that point and you should expect the settings to be default ...
Sorry about the confusion.
I work with JPGs and TIFs, preparing images for offset printing, sourced from stock agencies and individual photographers. I seldom work with RAW files. I really like the tools offered in ARC for adjustments because they are none destructive if I have to return to the source image for additional corrections. As I've stated above, I make the corrections in ARC, open in Photoshop to continue my image prep. Occasionally, when I return to the source file in ARC, the adjustments are gone. I make them again and open in Photoshop. Sometimes the adjustments are saved the second time and sometimes not. So, I'm not sure what the problem may be. Hence, my post here...