Users are blocked after voting

If you are using IP blocking with no timeout, whenever a vote is cast from an IP no further votes will be accepted, and anyone else coming from the same IP will only be able to view the results.

So, if you behind a firewall of some sort all the computers in the building will have the same IP address-- someone coming from a different IP would still be able to vote.

If you choose the "Regular Blocking" option on the security page there will be a 15 minute timeout on the IP but the cookie blocking will still be enforced. This cuts back on the number of conflicts that occur while still enforcing a fairly strict security policy.