Specific words in Page content causing 500 Error – anyone else have this problem

Through the process of elimination I have discovered that specific words, in the admin area of WordPress, in the content editor, when writing or editing, result in a 500 error upon saving.

For instance, one of these words is “select”. Another is “from”. The words are specific to the page being edited: that it, “from” can be added to all pages but the one causing the error, and for the one causing the error it cannot be typed in or pasted in. That word can simply not exist in that post or else a 500 error results upon saving.

This error is confounding me: has anyone else had this problem?

I am running a new installation of 2.6.1., Mibmo Pro theme.

I apologize that I am unable to send URLs of the site, but it is a password protected site. However, seeing the site will probably not help in diagnosing this problem.

Error log from the server:
[Sat Sep 20 10:35:47 2008] [error] [client 209.145.68.249] File does not exist: /home/pltrust/public_html/500.shtml, referer: https://pltrust.org/pages/wp-admin/page.php?action=edit&post=53&message=1&_wp_original_http_referer=http%3A%2F%2Fpltrust.org%2Fpages%2Fwp-admin%2Fedit-pages.php%3Fs%3Da
[Sat Sep 20 10:35:46 2008] [error] [client 209.145.68.249] File does not exist: /home/pltrust/public_html/500.shtml, referer: https://pltrust.org/pages/wp-admin/page.php?action=edit&post=53&message=1&_wp_original_http_referer=http%3A%2F%2Fpltrust.org%2Fpages%2Fwp-admin%2Fedit-pages.php%3Fs%3Da
[Sat Sep 20 10:23:17 2008] [error] [client 209.145.68.249] File does not exist: /home/pltrust/public_html/500.shtml, referer: https://pltrust.org/pages/wp-admin/page.php?action=edit&post=53&message=1&_wp_original_http_referer=http%3A%2F%2Fpltrust.org%2Fpages%2Fwp-admin%2Fedit-pages.php%3Fs%3Da
[Sat Sep 20 10:22:25 2008] [error] [client 209.145.68.249] File does not exist: /home/pltrust/public_html/500.shtml, referer: https://pltrust.org/pages/wp-admin/page.php?action=edit&post=53&message=1&_wp_original_http_referer=http%3A%2F%2Fpltrust.org%2Fpages%2Fwp-admin%2Fedit-pages.php%3Fs%3Da
[Sat Sep 20 10:21:16 2008] [error] [client 209.145.68.249] File does not exist: /home/pltrust/public_html/500.shtml, referer: https://pltrust.org/pages/wp-admin/page.php?action=edit&post=53&message=1&_wp_original_http_referer=http%3A%2F%2Fpltrust.org%2Fpages%2Fwp-admin%2Fedit-pages.php%3Fs%3Da
[Sat Sep 20 10:21:16 2008] [error] [client 209.145.68.249] File does not exist: /home/pltrust/public_html/500.shtml, referer: https://pltrust.org/pages/wp-admin/page.php?action=edit&post=53&message=1&_wp_original_http_referer=http%3A%2F%2Fpltrust.org%2Fpages%2Fwp-admin%2Fedit-pages.php%3Fs%3Da
[Sat Sep 20 10:20:24 2008] [error] [client 209.145.68.249] File does not exist: /home/pltrust/public_html/500.shtml, referer: https://pltrust.org/pages/wp-admin/page.php?action=edit&post=53&message=1&_wp_original_http_referer=http%3A%2F%2Fpltrust.org%2Fpages%2Fwp-admin%2Fedit-pages.php%3Fs%3Da
[Sat Sep 20 10:19:32 2008] [error] [client 209.145.68.249] File does not exist: /home/pltrust/public_html/500.shtml, referer: https://pltrust.org/pages/wp-admin/page.php?action=edit&post=53&message=1&_wp_original_http_referer=http%3A%2F%2Fpltrust.org%2Fpages%2Fwp-admin%2Fedit-pages.php%3Fs%3Da
[Sat Sep 20 10:19:10 2008] [error] [client 209.145.68.249] File does not exist: /home/pltrust/public_html/500.shtml, referer: https://pltrust.org/pages/wp-admin/page.php?action=edit&post=53&message=1&_wp_original_http_referer=http%3A%2F%2Fpltrust.org%2Fpages%2Fwp-admin%2Fedit-pages.php%3Fs%3Da
[Sat Sep 20 10:18:12 2008] [error] [client 209.145.68.249] File does not exist: /home/pltrust/public_html/500.shtml, referer: https://pltrust.org/pages/wp-admin/page.php?action=edit&post=53
[Sat Sep 20 10:18:02 2008] [error] [client 209.145.68.249] File does not exist: /home/pltrust/public_html/500.shtml, referer: https://pltrust.org/pages/wp-admin/page.php?action=edit&post=53
[Sat Sep 20 10:06:49 2008] [error] [client 209.145.68.249] File does not exist: /home/pltrust/public_html/408.shtml, referer: https://pltrust.org/pages/wp-admin/page.php?action=edit&post=367
[Sat Sep 20 09:51:34 2008] [error] [client 209.145.68.249] File does not exist: /home/pltrust/public_html/404.shtml

There is something I don’t get here ?? I could really use some help with this or even just see if anyone else has experienced this problem, it seems SO odd to me.