GPU fallen off bus using firefox?

two times while using firefox screen freeze. After looking at the log. it says GPU fallen off bus. There is no GPU load while using the desktop and not overheating. While this does not happen when playing games. I have attached two logs for the two times that happened.
nvidia-bug-report-dec7.log.gz (998 KB)
nvidia-bug-report-dec15.log.gz (1.1 MB)