This is the fourth time I have had this happen to me in game - enough to think it is a trend.
If your game suddenly crashes in an area that you believe should be working (either because you visited it before or because it doesn't have anything new that you have not already encountered), try this simple step before pulling your hair over a bug - reboot.
I am beginning to think that, when Oblivion crashes, some files may remain locked - either from Windows or from whatever anti-virus software you are running in the background. Next time you start your game, Oblivion may try to load that locked file and crash as a result.
You can't really be expected to reboot each time Oblivion crashes - that would be insane. But if after a crash, your game suddenly becomes unstable in 'safe' areas, remember to clear your system with a reboot before investigating a bug with your mods or load order.