My server all of a sudden is taking ages to start up, this is the only error I can seem to find: http://pastebin.com/iT59Fz4C Thanks in advance.
That doesn't appear to be the full error message. Also, it seems to be something related to GroupManager. I'm guessing the YAML syntax of one of your configuration files is invalid. If you could post the full stacktrace it might be easier for us to identify the problem accurately.
mcore doesn't appear to be compatible with 1.7 (or whatever version you're on). Have you tried updating it?