I'm assuming that you are encountering this at home, on your home network. If at work you need to speak to whoever manages your network. You are getting this behavior because your internet connection's OpenDNS settings are being managed and controlled by someone else.
If at home the first question to answer is if you intend to actually be using OpenDNS. If you aren't then you need to "disable" it by removing the OpenDNS addresses from the devices that are using it. That could be DNS address manually installed on individual computers and devices, or it could be used on your router. I can't be more specific than that because I have no idea how your network and devices are configured.
If you are intending to use OpenDNS then the most likely cause of this is either that your IP address is not properly registered or you are sharing your public IP address with someone who is also using OpenDNS.
The first situation is easy to cure, update your public IP address on the DNS dashboard, and install the IP Updater so that it updates it for you whenever your address changes.
If you are sharing the IP address with someone else you'll need to contact your ISP to see if there is a way not to share this address with others. If not then you'll either need to use OpenDNS FamilyShield to block a predeifined set of categories (but you won't be able to customize it in any way) or get a Netgear router with LPC, which while it makes use of OpenDNS does not rely on the same mechanism to provide customized filtering to you.
