I had exactly the same problem except there's a different reference for the pre-fetch file. I have just removed and re-installed Photoshop and the error message came up again during installation. The program worked OK but the error still appeared when I tried to access any of the help files.

I found this thread and followed the advice:
http://www.photoshoptechniques.com/f...ad.php?t=15959 and also: http://adobe.groupbrowser.com/search...e+written.html and find that deleting all the folders and files in Adobehelpdata except Packages and then running ahc.exe seems to have done the trick.

The adobe.groupbrowser looks like a useful resource. Hope this works for you!

Dammit! I've spent so long trying to get the help system running I've completely forgotten what it was I needed help for.........

Lol , dont worry. We'll be here when you do remember what it was.

Thanks for helping btw.

Have done everything. Still no resolution. Also, I notice that I am not able to view PDF files in Internet Explorer.

Someone suggested that I uninstall and delete everything related to Adobe, including any references in the registry

Sounds like a good idea to me. I dont know any other options atm.