Since I made a separate topic due to thinking it was more relevant like that (since most people were stating single player wise) I'll post it in here in stead so the other topic can get removed.
Problem Details: So whilst playing this song with two friends (Normal difficulty)
https://osu.ppy.sh/b/179353&m=0 - Rohi - Kodoku Egoism
Every time we get to the end off the song, it will auto fail. We didn't have this issue till the recent update.
When you finish the last slider (also the last note for the difficulty)
It makes the failed noise and returns to the multiplayer lobby.
So for this we had 3 people in total playing tag co-op.
It didn't happen on any other songs we played.
It only though, happened in tag co-op.
EDIT: Another song that does it at the end.
https://osu.ppy.sh/s/92509 - senya - Kanjou Chemistry
We were playing normal with hard rock
Video or screenshot showing the problem:
Unable to supply a video due to program not working and it happening a little to fast for the screenshot.
osu! version: 20141122 (latest)
Now the latest on this, today we all tried the songs we had a problem with in singleplayer, no problem at all.
Tried again with multiplayer and the problem came back.
So we tried it with pairing (only two of the three connected at the one time, rotating around)
Still had the problem.
If somebody is able to check it for themselves to see if they have the same issue?
Also I should note that we also have hamachi, so if anybody else here has hamachi running on their computer.
This "could" be the issue.