Details are needed:

First of all, what kind of Mac?  If it's one of the Macs with the infamous Intel integrated graphics (iMac, Mac Book, Mac Mini), we need not inquire further.  The number of bugs introduced by Lion in these machines is too numerous to go into.

Otherwise, it would be useful to know whether CS4 is updated to version 11.0.2, Lion to 10.7/2, whether you Repaired Permissions with Apple's Disk Utility before and after every install, upgrade or update of the application and the OS, as well *** what other troubleshooting steps you have taken so far.

Please read this FAQ for advice on how to ask your questions correctly for quicker and better answers: 

http://forums.adobe.com/thread/419981?tstart=0

Thanks!

____________

Wo Tai Lao Le

我太老了

PS— Beyond that, you may want to consider upgrading while you can, as CS4 will be out of the upgrade loop the moment CS6 is announced, and that should/could be in a matte of weeks.  The new Adobe upgrade policy will be one version back only as of CS6.

Same here. I just upgrade mi iMac 3.06GHz IC2D to OS X Lion 10.7.2 and notice that Photoshop CS4  (CS4 Master collection) refuse to open. it says "You can't open the application Adobe Photoshop CS4 beause PowerPC applications are no longer supported" !?

Seems all others CS4 Apps have no problem to open (After Effects, Bridge, Contribute, Device Central, Dreamweaver, Encore, Extention Manager, Fireworks, Flash, Illustrator, InDesign, Media Encoder, OnLocation, Premiere Pro, Soundbooth...) which make me think, if there is a bug, the bug is more probably in Photoshop.

I use Unistall Adobe Photoshop CS4 and re-install it from the DVD, with no better result...

CS4 can be MIGRATED from an older disk on which it is working by using the migrate app in the lion utility folder.

vince