I think the problem is no server configuration is the same. And I face this myself, I have 6 Dolphin 6.1.6 sites online without problems. D7 give als on 1 stage no problems, the one It give me headache is Orca. Yes the forum works, but the language will not compile.

What I will say is this, thats on the same server, you can have little problems to. So check out ,like other says every time, how the server is configured to the minumum what is needed. Yes I agree Dolphin 7 is a beast.