Okay...  Both Portals are now using the FCKeditor provider (v1.00.09) I downloaded this morning.  I noticed no differences.  According to your second suggestion, there could be a custom client script throwing things off.  I do have some client scripts being injected from the Default.aspx.vb Page_Load event, so I compared the two files, and they are identical.  :(

On a hunch, I changed the web.config in the non-production (working) version "Compilation" node to Debug=false.  Now, the only difference between the sites would be that my custom assemblies have the PDB files in the bin directory.  The problem still exists...

This leads me back to square one.  Do you have any other suggestions?

To further investigate this problem, I used the Web Development Helper plug-in for IE to see what the request was that is getting denied.  To my surprise and dismay, all requested files are returning a 200 status code.  :(

The files are all good.  I just installed the most recent provider this morning per the suggestion earlier in the thread. 

However, I thought you had me on the connection string...  I often migrate changes from my non-production site to the production site and will sometimes forget about something like the legacy connection string.  Alas, this was not the broken piece. 

Thanks for the suggestions though.  I really appreciate it!