Edit the global_start plug-in for the ad network and add this to the beginning of it: error_reporting(E_ALL ^ E_NOTICE); PHP:
That's a neat trick, Shawn! OK, that helped me to get things working. Thanks ever so much - I really appreciate it!!!
There was something wrong with the ad_network_ads_xxx.txt file. Either the file had gotten corrupted or the permissions were wrong - not quite sure. Replaced it and everything worked fine.