Create an .htaccess file in wp-admin. Place this code in the file.
<IfModule mod_security.c>
SecFilterInheritance Off
</IfModule>
I had the same problem. I deleted all the files and uploaded WP again. I still have the problem with the buttons flashing but they are not doing it every second now. It still takes longer than usual for the post page to load and refresh after publishing. I have two WP instillations on my server and the same problem with both. Went back to 2.5 on one and problem went away. Hoping for a fix to come out soon.
