UPDATED: Solved original issue by pulling original copy of PS out of my trash. Issue (not recogniing DNG and PSD file types) now appears to have repaired itself. Thanks. Number of views in the short time since posting, is quite amazing.
PS CS4 will not reinstall.
Error message is: Adobe Color Video Profiles CS4 Error 2.
Reason for reinstallation is that PS stopped recognizing DNG and PSD file types.