Have reinstalled oblivion 4 times,ran it with and without mods,tried sharing and security settings,and installing to public documents.Same outcome each time,a quick black screen,then it closes.Windows 7 pro,ATI 4650 card, dual core 8400 processor.Ran fine on XP,hates windows 7.
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You've applied all the relevant patches as well? I see you've installed it, but you never mention patches.
Also, do you have the latest graphics and sound drivers? I have Oblivion and it runs just fine under Windows 7 64-bit.