I've had *three* different types of crashes, and they keep occuring..
One is a player character whose gone through Oblivion andd Ko9, and then installed Shivering Isles, tried to load the character, and it was trashed. Every single it would load, show me where I'm standing, and then if I tried to move or hit TAB, *BOOM* right to the desktop with that "Oblivion* has crashed, click close"
Two is an even older character that was running on much lower graphics settings, so I loaded him up, changed the video settings, and it 'seemed' to run fine for about 2 hours, and then die. I even ended up setting a Chameleon Clock timer for 118 minutes that said "We're going down, save your game!" and it's still doing that.
Three, I started out with a fresh character (I know, I hear the groans of people who don't want to re-do everything all over again..) but I ignored *ALL* references to the Shivering Isles quest and went adventuring in all different directions, and nothing happened, no crash, so I got suspicious, and started the quest, and *boom*.
I am running V1.2.0416 and I highly suspect this patch is the problem..
I won't bother spewing my machine specs, but it's pimped and I can run practically anything on ULTRA settings. I highly doubt it's anything to do with my machine unless the nividia BFG NVIDIA GeForce 8800 Ultra OC 768MB PCIe drivers pack is an issue.