I just had a spat of CTD's after months of solid running. Turned out I had some mod weirdness going on. After I uninstalled, reinstalled and shuffled the mods back in I'm back to rock solid again.
Computers are not only stranger than you imagine, but stranger than you CAN imagine. Same solution as when your computer starts acting flaky: reboot. With software that means uninstall and reinstall. Don't forget to reapply the patch. (voice of experience speaks on that one

)