Played for 10-12 hours without any issues. Zoning from Bruma Caverns to The Jerall Mountains (after having discovered the Bruma spy) made the game freeze at loading page. The loading meter went slowly up to 100% and then it freezes. The music keeps on playing, tho. I could ctrl+alt+delete out of the game and Oblivion was "Not responding" and I was able to shut it down. I have the Steam GOTY version.
Haven't tried this a second time, tho. Will do that asap and get back with report.

Win 7 64-bit
i7 870 quadcore 2.93 GHz
GTX 260
8 gb ram

EDIT: Loaded the game again and had no issues zoning out after this.