It sounds like you are saying a different user can log into the same iMac and get Photoshop to open, is that correct? If that is the case something must be off on the user's profile. Check the Network Account Settings.
Yes, another user can login and launch Photoshop without a problem. When the 'problem' user logs into another computer, than he gets the same problems launching Photoshop. So, I know it is tied to the network user. What I am unsure of is how do I reset the user rights/priviledges? From a hardware standpoint, I can run disc utility and repair permissions etc. but do not know how to troubleshoot problems associated with one particular user.
Okay, I found a solution. Since it was just tied to the one network user, I knew it had to be one of the "support" files created in the User's ~/Library Folder. So, I did a little trial and error (after confirming it was indeed just Photoshop and none of the other CS4 suite apps.
Anyway, I deleted the ~/Library/Preferences/Adobe Photoshop CS4 Settings Folder. Then, when launching Photoshop this gets re-created.
So, all is well!