From BingWiki

Bug Reports

If you find something that behaves badly and you think it's a bug, write about it. Please be sure to include specifics like directory paths, file names, operating system and browser version.

Vague Error Message:

Attempting to preview a page results in the following error:

"The included file could not be read. Please try again, or contact technical support. S18"

It would be helpful if the error indicated which file(s) are not being included (for example, nav.html).