Kev,
Can you check if you also installed and enabled any JFBCProfile plugins? If so, please make sure you've only enabled the plugins for extensions you actually use. For instance, don't enable the Community Builder profile integration plugin if you don't have Community Builder installed.
If that doesn't help, go to your Global Configuration area and set Error Reporting to 'maximum'. Then, recreate the white page. Hopefully, there will be a nice error message there that will help narrow things down as to what's wrong.
Thanks,
Alex