Firewall issues (?) aside, this is the single most repeated mistake when using openvz for the first time:
eth0:1 Link encap:Ethernet HWaddr D4:AE:52:C7:F0:34
inet addr:192.168.42.171 Bcast:192.168.42.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:16
eth0:2 Link encap:Ethernet HWaddr D4:AE:52:C7:F0:34
inet addr:192.168.42.172 Bcast:192.168.42.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
Interrupt:16
Remove the two additional IPs you have from eth0, unbind them. Just keep 192.168.42.170.
Then you'll be able to use .171 and .172 for your openvz containers, otherwise they won't work.