Page edit downloads index.php

[MarkE]

This is probably something really stupid, but I have one page that cannot be edited - instead it just downloads the index.php file when I click on 'edit' in the page tree.

Any ideas?

[MarkE]

Needing to move on, I trashed and re-created the page. Weird dialog box when I trashed it:

I clicked OK and it did go into trash though. So I think it's fixed, but I'm still pretty puzzled about what happened....