Here's what's going on here, and why you don't recognize your own forum.
Firstly, SMF has some nasty copyright protection built into it. It sucks, but it's what they consider 'legal'. When the forum thinks you're not valid, it does just what it's doing to you now.
Secondly, try loading your header image. OOPS, it's not there. There is a problem with the image host you've put your image on.
Now, usually, this wouldn't be a problem, the template would go along and compile just fine. However, since you're timing out in the header, my guess is that the template can't compile past the header, and the copyright garbage come in and says "this is not a legal forum".
Now, just to be 100% safe, I tested the theme you're using on my own forum, and lo and behold, there is no problem, so this isn't a theme problem at all. This is an individual forum problem. My guess? You need to re-upload the image somewhere else.
I've put together my own little
image host, to help out members of these forums (and anyone else that wants it) and you're welcome to use that. It's not perfected yet, but for something as simple as this, you should have no problems.
Let me know if you still have problems after changing the header, or removing the image itself. You should (note: should) be able to login to the admin area to fix that. If not, I may have to do it manually which will not be easy.