may be this works:

  Hi I had the exact same problem.Even contacted support by phone.was told to try uninstall then reinstall.I tried that .It did not work.However i read on some post in this forum something that worked for someone.I tried it and all is fine .I went to windows explorer/adobe help center/highlight Adobe Help Center and deleted the entire folder.Then thru control paneldid repair Photoshop cs2..[ i had the cd in cd drive ]and it ran thru all and completed the install.Opened Photoshop and simply opened the help as normal no problems at all.I then downloaded and installed the update to help center it is now 2.1..i had 1.0 all went well and is fine .I followed exactly as someone else posted ..and all works great for me..Ray Perry 

 i took this from here Adobe Forums