After six hundred hours playing Skyrim on PC, these are the misc quests which do not complete on my game.

> Get Derkeethus out of Cave
He followed me right to the door and then turned back, no dialogue option to tell him to follow again.

> Collect bounty from Skald
This problem has already been posted on the forums.

> Bring a Dragon scale and a Dragon bone to Esbern
I'm unsure if the bone and scale he wants belongs to a Dragon I can't kill (because Paarth is bugged), as he won't accept regular bone or scale.

> Escort Telrav to his camp
Did that, and the rest... this quest didn't finish correctly.

> Find the copy of The Wolf Queen, v6
I found this book before the quest was given to me, but the option to hand over the book and end the quest wasn't present in the dialogue box. So, I went and found a second book after it had respawned, there's still no dialogue to hand the book over.

> Speak to Degaine
I'm not sure how this screwed up, there's a map marker to locate this npc in Marketh but no dialogue options to engage him.

> Speak to Verulus about the Hall of the Dead
No location marker for this npc, probably dead... wasn't there a DB quest to kill this npc?

> Ask Aldis for Information about Angeline's Daughter
This was an early quest and left undone for a long time, npc location marker for this quest points to the ground in the guards training area in Solitude. Npc dead?

> Investigate the Bards College
The map pointer/arrow points to the correct npc I think, but there's no dialogue option to continue this quest.

I had both of these in my quest log for along time and then one day both vanished. I could select them and it would take me right to the character to interact with and both had no dialogue option about the quest. They stayed in my log for almost 2-3 weeks when I noticed they were gone.

> Bring a Dragon scale and a Dragon bone to Esbern
I'm unsure if the bone and scale he wants belongs to a Dragon I can't kill (because Paarth is bugged), as he won't accept regular bone or scale.

> Investigate the Bards College
The map pointer/arrow points to the correct npc I think, but there's no dialogue option to continue this quest.

Finished the Civil War quests by siding with the Stormcloaks, by any chance? (Cut for spoilers.)

Ah, thank you for putting the mystery to rest. That particular quest has been buggung me for quite some time! Hopfully, the developers are taking a keen interest in these reports.

Cheers.

For me the only quest bugged so far is The Black Star. I can get all the way to the end, but the game never acknowledges that I finished the part inside the star, and I always end up stuck inside. Only way to continue the game is to exit using console commands.

Hmm, completed 'Arniel's Endeavor' at the Mages Guild and recieved not end of quest items, namely 'The Dagger Keening' and 'Arniel's Shade' spell. Had a look round the net and found this on Wikia..

• "Encountered a bug where after completing the quest and Arniel disappeared, none of the quest reward items were left behind. [This could be because you stood too far away from his experiment...he advises you to step back, but ignore him, stand right next to crystal. This seemed to work for me, not sure if it really was the distance or just random chance.] Keening may be found in the room directly below, since it sometimes drops through the floor!"

Yes, I was standing right back after he told me to. Oh Bullocks! This sorta thing should not happen!