from your quote it follows that your X is trying to access hardware, which looks really strange for me.
1. are you sure, that NX does the same as Xvnc? it should not require any direct hardware including tty's then. Also this should imply some limitations imho.
2. You can try to grant access to /dev/ttyX devices to VE. To do so, use:
host# vzctl set VEID --devnodes /dev/tty:rw
host# vzctl set VEID --devnodes /dev/tty0:rw
3. I recommend to update to 014 kernel
It should be much better and more stable.
4. you can try to give me an access and instruction on what you run/how to connect etc. I can try to help a bit.