[WARNING}error loading operating system railcraft save data: not in GZIP format

[I have a problem plz help]

Title: [WARNING}error loading operating system railcraft save data: not in GZIP format

Version: 3.1.2

OS: Windows 7 Home Premium 64-Bit

Java Version: Java version: update 7 version 5(latest to date) 32 bit and 64 bit

Description of Problem:

When I launch my launch.bat(cmd) it loads the server completely normal but when it finishes it says every 3 seconds. [WARNING] error loading operating system railcraft save data: not in GZIP format. I have deleted my railcrat.dat under the world folder but it didn't work after that I haven't do anything yet and i do not know neither have what its called MCEdit neither i do not know and have no to a back up to my server. I play the server only with my friend

Error Messages:

error loading operating system railcraft save data: not in GZIP format

Error Log:

[XdeathringzX]

easy fix. delete your railcraft.dat in your world folder