While using NEI in Utility mode, the following error happened:
http://pastebin.com/Fi3k2bs6
Somehow I ended up with a stack of items in my hand (well, cursor). Attempting to return them to the NEI interface caused the client crash.
I've been having some issues with NEI.
On a side note, longer term testing of 1.1.5 of my server has shown higher ram usage than in 1.0.6 even with relatively few players online. Previously we had 40 users online, 6k+ chunks loaded, and around 3.2 gb of ram used. Now we're hitting 4 gb usage at 4k+ chunks and 25 users.
Also, I did not properly upgrade my version of MCPC+ (Idiot here somehow named it Tekkit.jar.jar, so it didn't replace the older version. Derp.)