I have the same setup and am having the same error. I have 8 plug-ins and none of them work. Plug-ins work with Lightroom 3 and Beta 4, but not Lightroom 4. I do not have CS5. I tried deleting and reinstalling Lightroom 4 and also reinstalled a couple of plug-ins to no avail. Hope this problem is corrected soon.
Europe, Middle East and Africa