[TYPO3] page is being generated and PHP fatal error

[Bing Du]

Hi,

Typo3 4.0.6

For some reason, one page started giving 'Page is being generated, If this
message does not disappear within 30 seconds, please reload'.  Whenever I
click the page link in the menu, I noticed the following error was
generated in the Apache error_log.

[client 129.186.197.119] PHP Fatal error:  Call to undefined function: 
encryptcharcode() in
/data/www/html/typo3_src-4.0.6/typo3/sysext/cms/tslib/class.tslib_fe.php
on line 3439

Line 3439 is:

 $out .= $this->encryptCharcode($charValue,0x61,0x7A,$offset);

This page used to work fine.  It has the following content elements:

Text w/ image
Menu/sitemap
Text
Menu/Sitemap
Text
Menu/Sitemap

The load on the site is low.  I also don't think it's related to
extensions because there was no new extension installed before the page
stopped working.  I checked Tools->Log on the backend and found one user
inserted and deleted some content on the page.  I don't understand why all
of a sudden, it started spitting ugly PHP fatal error.  What does
encryptCharcode() do?

Any clue what might cause the problem?  I'd appreciate any insight.

Thanks,

Bing