dragon age origins plot issues

Hello,

I have a very strange problem with my DA:Origins - it seems that every time I find myself somewhere around the Dalish, I'm stuck in the storyline. I played with the Cousland origin and went to the Dalish camp, did all the available quests but upon reaching the barrier and all questes associated with it, I can't progress further in the story - I usually choose to help the Grand Oak and I know the Oak Branch should help me get past the barrier but it's not showing up in my inventory. So I tried every other possibility - killing the Grand Oak, killing the hermit and stealing the pelt from his - none of which worked. 

I got tired of trying to figure it out so I started a new origin - the dalish one. I explored the elven ruins with Tamlen, there was a cutscene with mirror and then I woke up next to the mirror, instead of in the dalish camp like I know I should've. I can't leave the ruins.

I have the lastest patch installed and I played this game many times before, this is the first time something like that happened since I installed Windows 7 on my PC.

What I can I do?

Hanna