I was looking to add caching to a site which had been created back in the autumn of 2007.

So I went site settings -> modify all site settings -> site administration -> site output cache

 

and I got "List does not exist"

 

The only list that this page uses is the site collection cache profiles and that was there.  So looked at a site which I had recently created and repeated the exercise and it worked !

 

So I checked patch levels there were the same.  The only difference I could find was that the 1st site had been created pre-SP1 and the latter had been created post SP1.

 

To test this theory I created a new dummy site on the same web application as the site which did not work and that worked fine.

 

So took Chris O'Brien's deployment tool (http://www.sharepointnutsandbolts.com/2008/06/content-deployment-wizard-updated.html) and  exported the site which did not work. I created a new empty site as per Stefan's Grobner's instructions (How to create a blank site)and imported the exported site into it. Guess what - when I opened the site output cache no more list does not exist.  So I could carry on setting up caching on this site.  I also deleted the old site and imported the export into it and it worked there too.