Oh, yes, i remember this, i had that problem several months ago. it is very annoying. However, one day, i was bored cause i couldnt do my quest, so i decided to switch characters, on my other character, i noticed it wasn't working either. I was getting angry about this, so I just logged off. Then later on, I decided to log back on. I was on my character and noticed it was back up! I was very exited, and it has worked ever since. I either got lucky, or switching characters works, try what i did, and see what happens. Good luck.