After installing the latest version of Railcraft, the following started happening on my server:

https://www.youtube.com/watch?v=dGDMuNTtgVw&feature=youtu.be

I tried isolating the mods to see what was causing the problem, and it turns out to be Railcraft. Any idea what the problem may be, or is this an intended feature?

-MastaC

Known Forge bug. I suggest updating.