One of them is in Hiberheim and involves you helping out a rabbit. It requires that you have the Pet Pal talent. It's not a quest per se in that it doesn't have an associated journal entry, but there is content that you miss out on if you don't complete it. The good thing is that this "quest" won't actually start until you get close enough to trigger it, and when you do it's pretty obvious what must be done.
The other one is called Frederick's Blood Stone, in Luculla Forest. This is the one that's possibly bugged. Basically when you first get it, try to complete it as soon as possible otherwise something might happen that makes it impossible to finish the quest properly.
