Mitcho- Thanks for the response.
No one else has access to the settings. I run two wordpress sites (both use yarpp), but only one is having this problem. I always update the core and plugins to the latest release, so right now I am running WP3.4.2, but I've been having this issue for a while.
I backup the files and DB directly, so I do not have any backup plugins. Here is a list of the plugins used:
Akismet
All in One SEO Pack
Allow PHP in Posts and Pages
Google XML Sitemaps
Regenerate Thumbnails
Term Management Tools
User Role Editor
Wonderm00n's Simple Facebook Open Graph Meta Tags
WP Super Cache
WP Widget Cache
and of course: Yet Another Related Posts Plugin
Most of these are also used on my other site that doesn't have this problem, so we can probably eliminate most of them as a potential cause. If we do that, the only ones left are:
All in One SEO Pack
Regenerate Thumbnails
Both of those have been installed on my site for a long time, even before yarpp was installed, so they were definitely around before this issue started with yarpp. (I believe it began around January, but I am not totally sure.)
I know I tried installing some beta versions of yarpp around that timeframe to try to fix problems I was having with random posts showing no related.
Here are a few things I have tried, which have not solved this problem:
1) Uninstalled yarpp and reinstalled.
2) Deleting all transient data from the DB.
3) Making basic adjustments to my yarpp settings just to be a little different (i.e. raising or lowering the match threshold a little.)