Try opening up Opera, and go up to the address bar, and delete the whole
Http://www.thiswebsitesucks.com, and type Opera:config
After you do that go down to the Install section and put a checkmark in Broswer First Time Launch. Then, Click on default and the lil >> next to it, and make sure that under Preference URL it says
Http://xml.opera.com. Click on Save, close Opera, and soft reset. That should take care of your problem.
I tried that before, but tried it again. All it does is make Opera the default browser, which is great, but still doesn't make it the browser for the internet tab in TF3D. I've read some more about changing it and there is supposed to be an xml to change it in the /WINDOWS folder, but it doesnt exist for USCC. It's there for the sprint and version versions of TP, but seems like USC took it out or renamed it in order to keep us from modding it.