New post page won’t load

I just installed 2.3 – everything seems fine, except the “New post” page won’t load. “Edit post” page does load.

In fact, I only considered using 2.3 ’cause I need tags system. If there is a tag plugin for 2.0.x I can just drop this problem.

Any ideas? I found like z dozen topics about identical problem on the forums. None of them answered (with like half of them closed and marked as “resolved” without a single word except the problem description).