I had no problem with LR4, but did with LR4.1 and 4.2. I don't remember the order especially, i.e. I was changing laptops and somewhere along the way updated OS to Mountain Lion. Kept getting this error and its was a typical Adobe blank spot and most of the help forums weren't very helpful, despite efforts.
The answer for me at least is on the Adobe site at http://goo.gl/KjkHz which describes accessing the hidden library files, etc and gives fairly precise instructions on how to do it once you reach the Lightroom folder in App Support. You don't need to go into the Lightroom folder, Just click on it, get info and change all permissions to "read and write" rather than restrictive. You WILL find a folder titled simply "Lightroom" in app support -- or you're not in the right place.
I know how to access the hidden files, but I don't usually think about having to do something like this for a routine installation. FWIW, there is sometimes mentioned a problem with installs when NIK filters are installed. I have three sets including Topaz Suite, FilterForge and Tiffen. (don't ask). They are not a problem.
