If I recall, the instructions tell you to move the old ACR plug-in right out of that folder.
It could be that the .BAK version you left there is interfering with the function.
#1
I've tried it that way too after reinstalling the entire Suite.
#2
Is the new plug-in visible in Photoshop Help/ (Help - About Plug-in).
If it's not, then PS can't find it during it's scan at launch. Didyou download the proper version for your O/S?
Rob
#3
I'll have to check that. I unloaded all CS3 and manually deleted all entries in the registry. I reloaded and now I have RAW functionality back. When I get home I'll check the Plugins to see if Photoshop is picking it up.
#4