I haven’t verified this myself but I received a report today from Darren Collins of http://www.OneStopUnder.com in which he reports-
 
Adobe Photoshop CS2 for Mac OS X has a bug, where the installer creates illegally-named files in the Application folder. These files are reported by Disk Utility, but cannot be repaired. The volume header for that disk is also reported as corrupted. Adobe Illustrator CS2 for Mac OS X has the same problem.
 
The fix is pretty simple according to Darren-  
More background information and instructions for fixing are here:
http://www.onestopunder.com/2005/12/photoshop-cs2-illegal-filename-bug/