You may see this error when generating your PDF catalog:
Warning: set_time_limit() has been disabled for security reasons in /home/www/mystore.com/www/modules/scpdfcatalog/SCPDF.php on line 14
The error is triggered by your server.
There is a set time limit in the module's configuration, and your server has the same setting, which seems to be disabled, hence the error.
You need to enable this setting on your server to be able to generate PDF catalogs.