Do you send your DNS queries to OpenDNS? http://welcome.opendns.com/
Is your correct IP address information registered at https://dashboard.opendns.com/settings/ ?
If you have still problems, copy & paste the complete plain text output of the following diagnostic commands to here:
nslookup -type=txt debug.opendns.com. 208.67.220.220
nslookup -type=txt which.opendns.com.
nslookup whoami.akamai.net.