I’m having this problem with WP sites I’m moving to a new server. I’m beginning to think it’s a setting on the server because these same sites worked on the old server.
I deactivated all the plugins, backed up the database, installed on the new server – and it works fine until I start reactivating plugins. At some point, the admin screen goes blank when reactivating plugins. If I go back in the browser and refresh the page – no problem. No errors, and the plugin that caused the problem is activated.
However, when I log out I get another blank screen (no login box) and I usually have trouble logging back in again as well.
Like Dave, I am now searching the forums and this site for possible solutions.