A TES: Oblivion Question?

I decided to replay Oblivion again, the thing is, the first time I played it it wasn't so bugged. Anyway, so I'm at the Thieves' Guild final quest, The Ultimate Heist, I'm in the The Elder Scroll Library but something happens, when I sit in the Reading Chair a Blind Moth priest comes down the stairs and comes close to me, but as he stands near me it's like he sees me and battle music starts playing. The other priest, the one that was reading, also gets up and runs towards me and both of them just stand there staring at me, but they dont draw they're weapons or anything, just stare at me and do nothing. They don't give me the scroll. I read that it may be because of KotN expansion, so I deleted it (I wasn't that far into it's questline anyway, I had to go the Pilgrim's Way) and reloaded my last save, but it still gives me the same problem. How can I fix this? Don't know if it helps, but I'm playing on Xbox 360.