[Plus EMU] Thread Error: Error in thread RoomManager.OnCycle Exception

I have never gotten to get this fixed on plus/skybird emulator. What this does is it's usually in rooms that have about 5-10+ users in. The room unloads alot of time, disconnects the users and gets laggy for a bit then throws that error.
I have a tried a few methods but it hasnt helped. Does anyone know how to fix this it would be very helpful.

Code:

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Error in thread RoomManager.OnCycle Exception --> Not inclusive:
System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
  at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
  at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
  at System.Collections.Generic.List`1.Enumerator.MoveNext()
  at Silverwave.HabboHotel.Rooms.RoomManager.UnloadRoom(Room Room) in c:\Users\Administrator\Desktop\Emulator [L]\Plus Emulator\HabboHotel\Rooms\RoomManager.cs:line 638
  at Silverwave.HabboHotel.Rooms.RoomManager.RemoveTask() in c:\Users\Administrator\Desktop\Emulator [L]\Plus Emulator\HabboHotel\Rooms\RoomManager.cs:line 543
  at Silverwave.HabboHotel.Rooms.RoomManager.OnCycle() in c:\Users\Administrator\Desktop\Emulator [L]\Plus Emulator\HabboHotel\Rooms\RoomManager.cs:line 303

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