Problem with 404 error on /wp-admin/ in WordPress

I have just been moving my blog to new host. Everything was fine after I did it as described at WordPress Codex except admin panel.

When I was trying to login to Dashboard I got 404 error. There is one very simple solution for it. When I was moving files from my old host my ftp client set chmod of /wp-admin/ directory to 775. It won't work with this permission. All you need to do is to change it to 755 and it should be working again.