I am also experiencing this behavior.
Gnome 2.32.0
2.6.35-28-generic #50-Ubuntu SMP Fri Mar 18 19:00:26 UTC 2011 i686 GNU/Linux
Ubuntu 11.04
I originally saw this after upgrading to 11.04 from 10.10. I can't remember the exact date, but the issue was resolved a month or two back then showed up again recently.
I am also experiencing this behavior.
Gnome 2.32.0
2.6.35-28-generic #50-Ubuntu SMP Fri Mar 18 19:00:26 UTC 2011 i686 GNU/Linux
Ubuntu 11.04
I originally saw this after upgrading to 11.04 from 10.10. I can't remember the exact date, but the issue was resolved a month or two back then showed up again recently.