Admin on wordpress went blank, why?

Hi, I’ve been having troubles with this,… first, I migrated changes from my PC to an online server; then, the admin side went blank. So I googled around for a solution, and addressed all the common problems: blank spaces on wp-config, checked for plugin interference, etc. I’ve never liked using too much plugins, so I’ve been cutting down to 3 and prefer coding my own solutions into the template; and if is too complicated, go for a plugin.
So, I’ve decided to start fresh: deleted the folder on my server, and deleted the tables from my database. Downloaded the latest WP version (3.9.1), installed it to the letter, changed ONLY the critical data on wp-config (server, user, password, and db prefix) and tested, wp worked Ok. Went to admin side and nothing, blank screen. Its a fresh install!! why!!!
Checked with another browser, nothing. Another machine, nothing.
So I tried again, deleted the folder and created a new one, with another name. Followed all the steps again, same result. So,I deleted the folder again, the tables and this time downloaded the previous WP version, 3.8.2, installed it and the result, again, is the blank admin page. And WP insists that my cookies are off, I’ve checked (each time) and they are Ok.
I have two or three sites on that server, I thought that it could be the server; but all the other sites admins work Ok.
The .htacess? no, it doesn’t exists on this particular site folder; early this year I had troubles with it, but fixed it for each other site.
Another site I have on this server has a .htaccess file, and another doesn’t; both work Ok.
So…I’m running out of ideas, or maybe I haven’t looked throroughly enough…