403 when trying to view templates in theme/appearance editors

hello,
i am getting a “403 You do not have permission for this request” when i attempt to view any template in the montezuma appearance editor. i had this same problem with another theme, attitude pro, on another site on another server with another hosting company, however with that one it is only the CSS files. i went through the following troubleshooting process recommended on an earlier thread (since closed) from one of the mods in these forums on both sites:

• checked plugins one by one
• tried with twenty twelve theme, still did it
• checked for hanging around deactivated plugins using FTP
• checked file permissions
• changed permalinks to default structure

i got the same 403s no matter what i did with the above, including opening the file permissions on theme-editor.php wide. i believe this may have started after migrating the sites from my local to production servers. i am not getting these 403s on my local. also, i have my directories set up so that the index points to another directory for the wp files, however on the one site with attitude pro, the problem occurred before i set the directory structure. could either of these be part of the problem?

any ideas? thanks.

q