The following is what the console output:
Multiple 'X-Frame-Options' headers with conflicting values ('SAMEORIGIN, DENY') encountered when loading 'https://www.raindd.com/attachments/do-upload'. Falling back to 'DENY'.
about:blank:1 Refused to display 'https://www.raindd.com/attachments/do-upload' in a frame because it set 'X-Frame-Options' to 'SAMEORIGIN, DENY'.
jquery-1.11.0.min.js:2 Uncaught SecurityError: Failed to read the 'contentDocument' property from 'HTMLIFrameElement': Sandbox access violation: Blocked a frame at "https://www.raindd.com" from accessing a frame at "null". The frame being accessed is sandboxed and lacks the "allow-same-origin" flag.
Wasn't having the issue in Chrome. Fresh install of Opera 26. Board URL is set correct. Server forcing all traffic to www and https.