over 1000 zombies but just 5 players? reason for login problems?

[senior_hombre 1]

Since the day the 1.7.2 update came out i noticed that the server me and my friends are usally playing on, did not let us log in (we stuck at the "waiting for character creation" screen). At first we though it is because of the update but then we noticed that other servers work well (even 1.7.2 servers). After our server restarted two of us had a chance to log in and play without problem. I logged out for a short break and as i tried to log in again i had the same problem as before and could not play. But one on my friends stayed on the server and could play without problems but as noone else could login the player number droped as the time goes by and in the end there are just 5 players on it.

But one thing was strange, the max zombie count raised continuous, in the end there were over 1000 zombies on it (but just 5 players).

1. is it possible that there is some kind of zombie despawning problem?

2. could this be the reason that noone was able to login?

3. will this be fixed?

4. why does not affects all servers?