Some more tests tell that changing gtk/gnome or firefox/thunderbird themes has no impact on this bug.
I'm using an i386 version of Ubuntu on a dual core AMD64.
I couldn't find an existing bug that looks like this one, but there are so many that I may have missed it... sorry if this is the case...
I'm available for further testing / detailed information.
Some more tests tell that changing gtk/gnome or firefox/thunderbird themes has no impact on this bug.
I'm using an i386 version of Ubuntu on a dual core AMD64.
I couldn't find an existing bug that looks like this one, but there are so many that I may have missed it... sorry if this is the case...
I'm available for further testing / detailed information.