Comment 4 for bug 184244

I still can not reproduce this on Ubuntu 7.10 with firefox 2.0.0.11 on i386 with a nvidia graphics card (similar setup to you).

Just to be complete, could you install the Opera browser and test this issue using that?
To install Opera you have to add this line to the end of your /etc/sources.list file either using the command line or Synaptics (add Third Party Repository):

deb http://archive.canonical.com/ubuntu gutsy partner

It is a canonical repository, so it is safe/supported.

Thanks!