There are quite some crash reports with that signature: *https://crash-stats.mozilla.com/report/index/0402ff56-6430-4b23-98c2-650eb2111012 *[https://crash-stats.mozilla.com/report/list?product=Firefox&query_search=signature&query_type=exact&query=nsFrame%3A%3ABoxReflow%28nsBoxLayoutState%26%2C%20nsPresContext%2A%2C%20nsHTMLReflowMetrics%26%2C%20nsRenderingContext%2A%2C%20int%2C%20int%2C%20int%2C%20int%2C%20int%29&reason_type=contains&date=10%2F12%2F2011%2020%3A02%3A28&range_value=1&range_unit=weeks&hang_type=any&process_type=any&do_query=1&signature=nsFrame%3A%3ABoxReflow%28nsBoxLayoutState%26%2C%20nsPresContext%2A%2C%20nsHTMLReflowMetrics%26%2C%20nsRenderingContext%2A%2C%20int%2C%20int%2C%20int%2C%20int%2C%20int%29 nsFrame::BoxReflow(nsBoxLayoutState&, nsPresContext*, nsHTMLReflowMetrics&, nsRenderingContext*, int, int, int, int, int)] Looks that it is related to the layout or scrolling a container, but if Safe mode doesn't help then hardware acceleration isn't causing it. Are you using a special Windows theme or otherwise made changes?