Weird Bug In Vilkas/Farkas Quest?

[you know who else]

I recently took a mission from who I THINK was Vilkas (but it could have been Farkas, because I took this quest a long time ago and don't remember the details), called 'Trouble In Skyrim'. I had to go to Peak's Shade Tower and kill a Spriggan off, than loot a chest. As soon as I killed the Spriggan, it said that I had completed that part--and needed to go see Farkas.

I went to see Farkas. I can't speak to him about the quest, just ask the usual things. So I asked if he had any work for me, and he says: "Aren't you already doing a quest for Vilkas? Come back to me afterwards."

Okay, that's weird. The little quest arrow directs me towards Farkas, not Vilkas. And the next part of the quest specifically says 'Return to Farkas'.

I actually married Vilkas a little while back, so I go back home to ask him about it--but it's the same with him. I can only ask him the usual questions.

I've tried everything. I've made him follow me--taken him out of my house--and then tried to speak to him. I've revisited both Farkas and Vilkas a painful number of times. I've gone back to Peak's Shade Tower JUST in case I missed something, and explored the area around it. I've closed Skyrim--AND Steam--and then reopened them.

Nothing. So, now I can't complete this quest, AND I can't do anymore Companions quests, because every time I speak to somebody, they claim that I'm 'already working for Vilkas' so I should 'come back to them later'. Which is pretty annoying, because I really enjoy the Companions quests--and I'm the leader of the guild, so...

Help???

[Clever Monkey]

I will not tell you to use the console codes on this page but you probably will have to.
http://www.uesp.net/wiki/Skyrim:Trouble_in_Skyrim

companion quests are buggy at the best of times but once you add in marriage and other things the quests can really go screwwy.