goldenstate on "Login not working after update"

Hello,

Hope someone can help me as I am wracking my brain here. On TWO different sites, after updating to version 3.5.2 and visiting my site, I got that message something like "Wordpress must first update database" and had to press the button to continue.

After doing so (again on TWO different sites) my site looks fine, but when I try to login to the admin area, I get some sort of weird redirect and my username and passwords do not work at all. The sites were working PERFECTLY until I hit that update button.

Any idea what's wrong? Someone else must have this problem too...

Thanks in advance.