So basically spend all day yesterday and some hours today, oblivion game of the year edition comes with 2 DLC shivering isles, and nights of the nine, both don't work as far as I know, I googled shivering isles and they said if you wait for 24 hours you should get a quest pop up, I waited days, no such pop ups, so I decided to try add the rest of the dlc, the minor dlcs some of them did indeed work and I got quests working.. so I got like 4 out 10 dlc's to work the rest don't seem to want to work.. and have no idea how to find out if these dlc's are broke..or even enabled in game, checked everything, re downloaded tons.
Are they retail discs or iso? If they're iso and you have the ability to burn try that way, put disc 2 and install the content that way.