My apologies, when you said you were just going to reinstall 7.5.6, I thought maybe you were doing an actually full new install just to test with.
What you probably want to do at this point is just get it back to the original issue where the reply ended up with a blank screen. At that point, open up a support ticket with admin info to the forums and ftp info to the server and we'll take a look at what's going on.
