Thanks for your trust for giving me access to your admin site, highly appreciated.
I was able to find the problem.
The issue is probably caused by the plugin System - RokGZipper.
After disabling a few and after disabling RokGZipper the page showed up.
So, I re-enabled the others and left RokGZipper disabled.
Therefore I tried to exclude almost every file of the Ninjamonials Rotator but to no avail.
The best solution I have right now is to leave the RokGZipper disabled in order to make the Ninjamonials Testimonial Rotator work on your site.
I hope you understand what I'm trying to explain.
If you have further questions, please do ask.
Thanks again for your assistance on this.