Co-op: Don't see the group

I had this bug a few times now, and it's annoying.

I am grouped with a friend, we sign up for a co-op, and we join.
When inside, I don't see the damn group window, I can't even talk at all, Area chat seems to be disabled there, and groupchat doesn't work, cause, I'm not in a group.

I can still run along, get credit and loot for everything. But since I'm usually the only one who tries to heal it's damn annoying not seeing your groupmates HP bars and stuff like that.

I guess I could log out or so, but I figure that removes me from the instance.

This does not happen to me - but does to my GF. It drives her nuts. We haven't figured out what does it. :(

This happens to me quite a lot.

It can get pretty annoying.