Hello Leshb,
You may be trying to run something on your website that does not agree with the default mod security settings. Fortunately, you can actually control this setting. To disable modsec settings for your site go to this article and it will walk you through the change in your Cpanel.
Disable Mod Security
If you have any further questions, please contact technical support or leave a comment at the bottom of the page.
Regards,
Arnel C.