My MAC recently updated to version 10.7.5. Now I can longer launch PS CS 5.1 in 32-Bit Mode. This is important to me because I have a plug-in that only works in 32-Bit Mode.
It is checked off in the System Preferences to launch in 32-Bit, however will only launch in 64-Bit.
Are you sure you 'checked it off in Ssytem Preferences' ? Because that is NOT the place to do it.
Using the Finder, navigate to the Applications -> PHotoshop CS5 folder and eventually you'll find the actual Photoshop executable. Then do a cmd-I (get Info) and that is where you do it.
Well it took a complete reformat, but I got PS working in 32-Bit again. Mac Defender is a joke. Don't waste your money on it. From what I am reading it's nothing more than malware for a MAC that you pay for.