Note, this is a site from where I first started supporting MODx in 2006-7. At some point, such as the use of manager to install or update a plugin, or update MODx itself (maybe unlikely, since IIRC 0.9.6 was the thing before I started), /manager/includes/config.inc.php was CHMODded by MODx to 600 instead of 644.
This gives a 500 to server response checker and causes zero html to be output to search engines. Of course causing the site in question to be excluded from all search results, bar any text files it finds in some subdirectory.
I found this bug by systematically removing php code from index.php, until I hit the include and knowing there must be no 777 files in the path of bots, I checked the CHMOD.
I found no forum for bug reports at all. So I post it here and hope mods will move it to where it belongs.
Indeed, the blame might not be the manager. Certainly, I did not change the attributes, so the source is a component with access to the file. But there are a few sites out there that perhaps might not easily be upgradable to MODx 2, so it would be a nice gesture with a small fix.
If this fix has already been released, please keep this post anyway to be found by others searching for the same error. This will save face for them visa vi their web hosts, who will stoneface them and say that their tech support doesn't include debugging scripts. In this case, they were semi-correct.
I can provide proof of this on demand, but so can any user of 0.9.6 of course.