I've been trying to figure out what to do with this for the past 2 hours, and I'm getting a little peeved off. The entire server startup log is below, but it has something to do with the libsandstone mod, and it won't allow the server to load. I'm not sure what mod requires this, but any help would be greatly appreciated.
(So I couldn't put in a spoiler, here's a link to the log. It's on my personal site, and it's just the log.)
http://skylorenations.com/forge-1.7.10-libsandstone-error.html