Problem Solved - mb_strpos warning partially to blame
The problem described above has been solved - here is the issue in case others have a similar situation.
I started receiving mb_strpos warnings whenever I attempted to view a category or product list. I couldn't fix it - so I did the wrong thing: I suppressed the php warning messages.
QUESTION: Why am I receiving "Warning: mb_strrpos(): Empty haystack in pp-inc.php on line 360" when I attempt to view a category without products?
I then tried to customize the header incorrectly: by modifying the ppopen template. Not surprisingly, not only didnt' this work, but now it started to throw "Warning: Cannot modify header information " messages. But of course, I never saw these message because is suppressed the php warning message.
After realizing that reviewpost was not writing cookies, a small lightbulb went off and I turned off the php warning suppression. And then of course I saw this wonderful warning message that told me exactly which template was causing the problem (ppopen.tmpl).
I replaced the ppopen.tmpl file with one from the original distribution (since Omegatron told me how to use server side includes to customize the header). And now things work perfectly!
Last edited by thompson00; December 17th, 2004 at 10:22 AM.