We need to check the log file to put more light. Use Drop Box http://db.tt/v0soB3XD to upload the log file if the issue doesn't get resolved after following the steps below.
Log File location: c:\program files(x86)\common files\adobe\installer
>> Uninstall Photoshop 5.1 from the Creative Suite Standard 5.5 installer.
>> Uninstall it from Control Panel - Program and features.
>> Restart the computer.
>> Install Photoshop from the Creative Suite Standard 5.5 disk.
>> Run the update.
Thank you for the suggestion. Tried it but it did not work when I just uninstalled photoshop but it did solve my problem when I uninstalled and then reinstalled from disk the entire Creative Suite. The original install was a trial download and perhaps that is why I had the problem. Thanks again.