I have AJAX Scroller displaying articles from a specified category that contains 3 content items, but only the first 2 content items are being displayed…
http://www.catchlight.com/dev/naturalgardener/

I tried various settings for "Nr. of items displayed" and "Max number of items" in the module settings. I also checked file permissions as described in the FAQ and I checked to be sure overflow: hidden; was not being used by the module position in my CSS.

I would greatly appreciate any help with this problem.

File permissions are set to 664 on my server. Per your FAQ, I tried 644 on this file and it did not help.

The directory "modules/mod_ajaxscroller/" is set to 775 by default and I changed it to 755. This does not make any difference either.

Also, your FAQ mentions the directory "modules/mod_ajaxscroller/mod_ajaxscroller/", but I do not see that directory on my server?

Hmmm. OK, I will look into that.

Thanks,
Howard

I said everything that I could about it. I can't fix your server. Present your web host the link that returns 500 Error and tell them to fix it:
http://www.catchlight.com/dev/naturalgardener/modules/mod_ajaxscroller.php?m=84&d=prev&c=0
If you try http://www.catchlight.com/dev/naturalgardener/modules/mod_ajaxscroller.php?m=84&d=prev it works, so the problem is in &c=0 in query string. It is some stupid security setting somewhere on the server that blocks it.