I had to reinstall LR and every time I start it now, I get an error message saying "an error occurred while attempting to change modules". I get a blank grey screen, no side panels, but at the bottom it lists how many photos are in the catalog and in the folder. There is no filmstrip. Clicking on Preferences does nothing; no dialogs or anything. It used to run fine.
OSX 10.9.5, The only software issue I have had is not being able to update to Yosemite.
PS: I have installed LR4 and got the same results
There is a good list of possible work arounds here:
This is what fixed it (I think. I hope!) for me:
NOTE: Use this solution if you are asked for your serial number after you relaunch Lightroom after getting this error.
The Lightroom folder inside Application Support could have the wrong permissions preventing Lightroom from writing to it which can cause this error.
Important: (Mac OS) Apple made the user library folder hidden by default with the release of Mac OS X 10.7. If you need access to files in the hidden library folder to perform Adobe-related troubleshooting, see How to access hidden user library files.