When I open my Gmail calendar I get repeated errors that "calendar.google.com:443 uses an invalid security certificate" and I have to click cancel several times to use my calendar. I also get this error anytime I try to make changes on my calendar. I am also receiving the error "services.addons.mozilla.org:443 uses an invalid security certificate" anytime I go to tools then addons to try to use themes or plugins. I have already tried to disable plugins and themes as well as safemode and I still have this problem. It worked just fine for about a month. This is the second time I have removed and reinstalled Firefox to try to correct this problem. It has been present on two different laptops using the same 3g sprint connection one on XP and this one is using Win7 32-bit.