Photoshop Elements appears to use Opera version 7 internally and launches it at startup. On my machine, Opera 7 was crashing in the strcat function and preventing Photoshop Elements from starting properly. I have Opera 9 installed on my Mac. Removing Opera 9 and all traces of Opera related files enabled Photoshop Elements to start, but I believe that deleting just your preferences would prevent the crash. Opera 7 may be trying to read Opera 9 preferences and crashing when it finds something unexpected.