Especially Jim Perrin for his SELinux config.
No problem. Glad you understood it through the atrocious grammar errors and typos.
Seems that for Cacti, mbstring.func_overload must be set to 0 (I had it set to 7), and session.use_cookies to 1 (I had it set for 0). The mbstring.func_overload was responsible for regular expression errors. session.use_cookies was responsible for login loop.
Hmmm, interesting. I've not really ever looked that closely at the settings cacti expects.
I simply added following to /etc/httpd/conf.d/cacti.conf (from Dag's cacti RPM):
php_flag mbstring.func_overload 0 php_flag session.use_cookies 1
Nifty. Glad you got it working.