POSSIBLE WORKAROUND: I was also facing the same problem in Ubuntu 10.04/Firefox 3.6.3/nVidia 195.xx driver/XOrg 1.7.6. The work around was reinstalling/Upgrading Firefox using ubuntuzilla. That seems to have fixed the problem.
POSSIBLE WORKAROUND: Upgrading Firefox using ubuntuzilla. That seems to have fixed the problem.
I was also facing the same problem in Ubuntu 10.04/Firefox 3.6.3/nVidia 195.xx driver/XOrg 1.7.6. The work around was reinstalling/