Thread:Project:Support desk/index file exception on save

The exception error is

Forbidden You don't have permission to access /mediawiki/index.php on this server. Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

It occurs when trying to save or preview a page (not just this one)

An error is caused by certain URLs and not others. For example, converting:
 * "http: //www.imc-cim.org/..."
 * to
 * "http://www.imc-cim.org/..." (i.e. dropping the space between the : and the //)

...triggers this error. In fact putting any url there seems to trigger the error.

Earlier in the page, the word "poker" triggers the error. This is avoided if a space is replaced (po ker) and "casino" has a similar effect.

I've looking for a solution for a couple of days without success. Any clues would be most appreciated.

This issue may be related to: (Resolved)Are there forbidden character sequences that can cause 404 errors? except I could not figure out what had been resolved.