Unable to enter dashboard after upgrade to 3.4.2

Can’t do any admin work after installation of update 3.4.2. I have about 15 wordpress sites and all but three updated okay 9.26.12. Of course, these three are the most important ones. Fuller story: The sites are live and available. I am able to log in using the https://www.site/wp-admin page or https://www.site/wp-login.php, but the dashboard will not show up. This is true for both an artisteer themed page and a basic WP 2010 theme. What may be common among them is a plugin that isn’t compatible with 3.4.2. These three sites have the most plugins.
plugins I recall using are
all in one seo
seo by yoast
google analyticator
akismet
Jet pack
google xml sitemaps
wp-db backup
wp-twitter retweet button
share this
fast secure contact form
facebook like box