Strange link

Hi! 
I put the files for PhpBB in;
mydomain.com/forum/

When I go to  mydomain.com/forum/install/index.php  this shows up. (See attachment)  
I find it strange because Dolphin has nothing to do with what happens at those pages, it is all PhpBB over in those directories right? Why do I get a Dolphin message in a PhpBB directory? 

And how do I solve it? 

//Confused.  

It gets worse: 
I create test.html and put it in the main WWW-folder next to all the Dolphin files, I go to mydomain.com/test.html
and it loads with no problem.

I create the folder "forum" and put the test file in the folder, then I go to;
mydomain.com/forum/test.html and IT CAN NOT LOAD.

How  strange is this? 

And I already have a functional wiki at mydomain.com/wiki that  I had no problem installing....

 

I tried to post in the /wiki/ folder and put the test.html there and go to; mydomain.com/wiki/test.html and it loads. 
Its like I cant create any new folders.

Is this a hosting issue? Or a known glitch?  

You have a lot to learn!

Do you know what an .htaccess file is?

Newtons right.. the Dolphin .htaccess file is running the show and it doesn't like that you're trying to replace it's forum.