Hey there,
I just got informed by a user and found the bug afterwards on my own that there are some notifications saying 'someone commented on your event'. The link does not open the event but for admin the link to the event works. Pretty weird, I put some more details below or above, no idea how you see it.
Another thing I just noticed is that the stream entry contains two links. One is the eventtitle and the other the link under the time the post was made. The title link works, the other one does not.
Not to forget that the user did not create that event though she got a notification saying so.
The green link works, the red does not. Inside the notification the red link is used.
I am really sorry of finding weird things!