Right sidebar broken after upgrade to 7.x

This is the site:

http://florin.myip.org/blog/

I used Pushbutton for a long time with previous versions of Drupal, it's a very good-looking theme. Today I upgraded to 7.x and it looks like Pushbutton does not display the right sidebar correctly anymore. Before, the blocks were displayed at the top of the sidebar; now they are vertically centered, so if the page is pretty tall (most if not all of them are), the blocks are displayed waaay down the page. Some blocks are not displayed at all.

I tried to disable the blocks, then re-enable them - didn't help.

I configured this theme with the exact same blocks like Garland (which works correctly) - didn't help.

I'm out of ideas. Help please?

Current configuration:

Left sidebar
Recent blog posts
User login

Right sidebar
Syndicate
Management
Navigation
User menu
Links

Content
Main page content

Header
No blocks in this region

Footer
Powered by Drupal

Highlighted
No blocks in this region

Help
Contact page help
System help