1) It seems that you have made something like
"ifconfig venet0..." on host and in VE. It's wrong. You don't have to do it! Routing is also done automaticaly. Just use the commands vzctl set --ipadd IP --save and similar!
2) Here is a small description, what I've done to get it all work:
a) Add "options ip_conntrack ip_conntrack_enable_ve0=1" to /etc/modprobe.conf and reload this module with modprobe.
b) My external IP is 192.168.0.239 on eth0. VE's IP is 10.0.0.2.
(If you have more than one interface don't forget to tune VE_ROUTE_SRC_DEV variable in /etc/vz/vz.conf as you wish)
vzctl set 200 --ipadd 10.0.0.2 --save
vzctl start 200
At this moment you can only ping HOST from VE (and back to front of course)
c)
echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -s 10.0.0.2 -o eth0 -j SNAT --to 192.168.0.239
After that I was able to ping "world" from VE.
If you'll have problems you can give me an access to the node, if possible, and I'll try to help.
Good luck!