Tim.
Thank you for responding. I used an old course as a template and "restored" it to a new (previously non-existent) class. I noted that the resource links had all been updated - see link below. So I used the editor to update the link lcoation for the text to match the location (url) of the resource. Several days later, someone pointed out that the urls were different again. What I noticed today is that the url for the text and the forum are the same when you access the forum from the Activities Block, but the url for the forum listed as a resource (the one that is provided automatically with the little icon) is not the same.
From the link in the text http://cpopd.com/mod/forum/view.php?f=149
From the page listing the forums (accessed from the Activities Block http://cpopd.com/mod/forum/view.php?f=149
Resource link (with icon) when restored from template (different from the link in the template) http://cpopd.com/mod/forum/view.php?id=567
But I had changed the text link to be the same as the resource link number. I am able to see the forum regardless - so I assume there is a cached version somewhere. But where? And how do I get rid of it?