CMS Made Simple Forums

On one of my sites (running 1.11.7) it is impossible to edit pages.
All I'm seeing is a thin white rectangle where the editor should start, and the source code ends suddenly after the title element of the embedded page.
This happens whether or not I disable TinyMCE, and in a couple of browsers. The last logged PHP errors are a couple of hours old, so there doesn't seem to be an error being generated.

Is there anything that I should try or check before a reinstall?

it's probably an error in your template. e.g. Are you still using {stylesheet} instead of {cms_stylesheet}

Yes, that was it. The site would have been my first CMSMS one - about 6 years old.