I've been lately trying to start the SI quest but for someone reason i can't sit down therefore i can't start the quest because to start it the dude asks you to start. When I try to sit, my character just freezes and he doesnt sit but i can still open my menu and my inventory. I am then convinced that I got this error but completing the KotN quest. I am running Oblivion on pc, plz help me deal with this error, thx

Try reinstalling, sounds like some coding got messed up.

It's caused by an animation bug associated with the Knights of the Nine. This is fixed on PC by the http://www.uesp.net/wiki/Tes4Mod:Unofficial_Official_Mods_Patch#Unofficial_Official_Mods_Patch.