If you watch the splash screen as the program loads after a few seconds you should text on the left side about a 1/3rd of the way down telling you what's loading. This can give you a clue if it get's stuck when something's loading. Could be a problem with a 3rd party plug-in. You can also reset your preferences to the default settings by holding alt when splash screen appears.
Try also to delete the media cache manually
go to Mac:/Users//Library/Application Support/Adobe/Common
Please do NOT add images via the "attach files" box, as you are then forcing everyone to DOWNLOAD the file to view it outside their browser. Drag/drop the image files directly ONTO your reply box so other users can see them without needing to download unknown strange files. Thank you!