This has happened once before. One day, photoshop decides it doesn't want to start up. During the loading screen, it just stops on "Reading text global resources."
Luckily, after a short google search, I found this:
photoshopnews.com/2005/01/07/photoshop-freezes-when-you-start-it-cs-on-mac-win/
Here's the fix:
You need to delete the "New Doc Sizes.psp" file. It is located at:
C:\Documents and Settings\[username]\Application Data\Adobe\Photoshop\9.0\Adobe Photoshop CS2 Settings
Fin.
