A number of links pointed at old URLS (domain name and path) for the mysteryquests, changed all those to point to current URL.
Also fixed a number of other errors such as links that point to non-existant directories, links on the French site that point to the English site, etc.
I think I've now caught up with all the errors reported by users through MF to me.
Access to the interpretations and teachers' notes sections is restricted. Authenticated users get values placed into session variables which are then checked on the relevent pages. For some reason, on the new server those values cannot be read from the session array. It did not appear that the subsequent pages started a new session (looked up the php reference on that and no files were created in the sessions dir), just that they couldn't read the values in the session variable. Nor did it appear that the problem resulted from different servers in the cluster writing to different temp or session dirs. Ryan checked on that for me.
I ended up passing the SID explicitly in the URL as a GET argument, and even though the subsequent pages make no use of that GET argument, the session array values are now available. So, it now works, but we're not sure why.
In testing the CanMys site instance on the new server cluster, a number of problems with the site (not so much the new server) have come up which I have had to address.
First: the privileges on many files were wrong, causing problems with the suPHP on the new server (the php is invoked by clicking on an image, which goes and gets a larger version of the same image using PHP). I fixed the privileges so they were more secure and compatible with PHP.