Re: Index was outside the bounds of the array
That error would seem to indicate that it looked up the required params for the stored proc "mp_Pages_SelectOne" and the procedure only wants one param instead of the 2 being assigned. All I can guess is you have an old version of that procedure. Although there were no schema change in 2.1.5 there were changes over the last few versions for stored procs so you need to run the script 3CreateStoredProcedures.sql that came with the 2.1.5 release.
Hope it helps,
ps, when you post errors using the editor you should paste the error in using the "Paste as Plain Text" toolbar (see the clipboard icons in the toolbar and mouse over to see their names). This will prevent the format errors that occur when pasting html fragments that are invalid or missing a closing tag somewhere.