Server error, players seem to be logged in, but server is down

[ChrysWhyte]

Launcher/pack Version: Tekkit 2.1.1 server

Operating System: Windows 7 64-bit

Version of Java: 7 update 3 64-bit

Description of Problem: I have not found a pattern to when this happens, but at times my server throws the error in the pastebin, everything seems normal as if people are still there, but in reality they all drop out and joining the server is impossible.

Error Messages: I have no error log from a client

Link to pastebin of log: http://pastebin.com/vjF6NiJJ

Plugins: WorldBorder, RecipeManager, DiskDriveFix, WorldEdit, PermissionsEx, ChopTree, Pail, DisguiseCraft, ProperTime, PailPlus, CommandBook

I have updated commandbook to 2.0, and am running the last version of PermissionsEx (Which lists it is for 1.2.3-R0.1 but starts up fine, I have assumed up until now that if there was a real problem it would error out on startup. Could this be a problem? I also used to run dynmap (latest version) which also seemed to work fine even though it does not state compatibility)

I see some buildcraft stuff in there, but I haven't really come across anything useful googling. (I also get some occasional buildcraft error creating pipe type 0 (class=null) errors, dunno if that's related)

[ChrysWhyte]

Used IRC since not posting at the time most people are on just gets me sweeped down. Stupid buildcraft builders.

Feel free to close or whatever