Error 403 Forbidden with template edit

[iNSiPiD]

Another bizarre thing has cropped up since the .10 upgrade.

When I try to edit a template file I receive a 403 error. I can't even do a Preview from this screen.

I can edit page content and change other settings. Group  settings show permission for Admin to edit templates.

Please help. Did I do something stupid somewhere??

[Ted]

Reupload admin/edittemplate.php and lib/classes/class.template.inc.php

Does add template work?

You really need a new FTP client. 

[iNSiPiD]

I just don't know know what is going on. This morning everything works as expected. And this is after repeated logouts yesterday over a period of a couple of hours.

I have multiple people working on the site. No one but me should be logged in as Admin but, if they were, could this affect my login and editing abilities?