After upgrading to 3.6 from 3.5,I noticed my previous lens profiles were missing from the lens corrections panel.
went online to Adobe and downloaded the lens profile creator and profile downloader.Still couldn't locate the
profiles that came with the earlier versions of LR3 but did find out where the profiles should be.
Finally reinstalled LR3.4 to a different hard drive than my C: location. All of the original profiles for LR reinstalled to the correct location
C:\Documents and Settings\All Users\Application Data\Adobe\CameraRaw\LensProfiles
As well as the new ones that shipped with LR3.6
I'm running a PC with windows XP 32bit version.
Not sure if this is a bug or not but reinstalling the older version did the trick.
I also made a backup copy of the Camera Raw folder just in case.
Hope this helps anyone else.
Have a Great Holiday Season and A Very Happy New Year
Gerry Robinson
www.grobinsonphotography.com