Sorry, I haven't replied in a while.
Are you Running Java 6 or 7? have you tried updating Java? Whats your java runtime commands? Which Mod pack are you running. Did you recently update or change anything on the server? Can you run a Java Profiler to see what java is up to?
1. I'm not sure, but I may be running java 7 (which could be the problem)
2. I have tried updating java, and it says that I have the latest jre, but the jdk is Java 6, because I have run into many Java 6-Java 7 problems in the past relating to minecraft and ftb.
3. I'm not sure I know what you mean?
4. FTB Ultimate
5. Yes, I did have some problems with the MinecraftForge state engine corrupt or something like that, so I restored a time machine backup of my world.
6. (I can't install the java profiler because my eclipse is kinda funky when it comes to installing plug-ins)
Also, I left out some critical information by accident! The server freezes up when I'm on the server and I go near Factorization Ore Processing machines. These machines are the Mixer, the Crystallizer, the Slag Furnace and the Grinder.