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The problem seems to be a misconfigured system. Let's see.
For the blank pages, you need to enable php-debugging, so the system can report what is causing those pages to break. There's two ways of doing that: via the admin control panel, and by going directly into the database (for those that do not have access to the admin panel).
I see you have difficulties going to the admin panel as well, but these problems may very well be related. The loop of 'logging you in for the first time' is probably caused by insufficient rights on the server. Make sure that the cache/ temnplates_c/ and uploads/ folders are writable by the system (CHMOD 777 on *nix servers). If these are not set properly, the system can't write the administration menu file to the cache/ folder, an action that is performed the first time you log in (in fact, that's how the system knows you're a first-time admin: the admin menu file is not in the cache/ folder).
Try this first, if there still are blank pages, we'll see about those later.
Herko