Strange crash on save.

[infra001]

Server Crash Report
===================

Operating System: Microsoft Windows NT 5.0.2195.0
.NET Framework: 1.1.4322.573
Time: 22/12/2003 14:45:12
Mobiles: 18908
Items: 366286
Clients:
- Count: 66
Exception:
System.NullReferenceException: Object reference not set to an instance of an object.
at System.Text.UTF8Encoding.GetByteCount(String chars)
at System.IO.BinaryWriter.Write(String value)
at Server.BinaryFileWriter.Write(String value)
at Server.Mobile.Serialize(GenericWriter writer)
at Server.Mobiles.BaseCreature.Serialize(GenericWrite r writer)
at Server.Mobiles.BaseMount.Serialize(GenericWriter writer)
at Server.Mobiles.Horse.Serialize(GenericWriter writer)
at Server.World.SaveMobiles()
at Server.World.Save(Boolean message)
at Server.World.Save()
at Server.Misc.AutoSave.Save()
at Server.DelayCallTimer.OnTick()
at Server.Timer.Slice()
at Server.Core.Main(String[] args)

Any ideas what caused this ? It crashed during saving.
Also I had to revert to a backup just to get it up again.

[Phantom]

Your custom changes caused it.

at Server.Mobiles.BaseCreature.Serialize(GenericWrite r writer)
at Server.Mobiles.BaseMount.Serialize(GenericWriter writer)
at Server.Mobiles.Horse.Serialize(GenericWriter writer)


Looks like thats the source.