Just to clarify, with lines 192 and 197 commented out, no fatal errors are created, but neither is a PDF view of the daily or weekly prayer request which could then be printed by the user. Results are just pasted back into original frame.
It appears that there were some changes in the Joomla 1.5x PDF creation scripts. I believe these changes should fix this issue:
Rename the "components\com_prayercenter\controller.php" file on your site to "controller.old". Unzip the attached "controller.zip" file and copy the "controller.php" to the "components\com_prayercenter" directory of your site.
Rename the "components\com_prayercenter\helpers\pc_class.php" file on your site to "pc_class.old". Unzip the attached "pc_class.zip" file and copy the "pc_class.php" to the "components\com_prayercenter\helpers" directory of your site.
I will include these changes in the next version of PrayerCenter.
NOTE: Use these files on version 2.5.2 of PrayerCenter only.