basic 10!!
Anti Virus and the like can be a bit overly paranoid sometimes and block stuff for no real reason, anyway I usually use this site if I need a web proxy in a hurry. http://www.samair.ru/
Best idea would be to make a list of proxies in the correct range, then run them through this to root out the dead and timeout ones. http://www.samair.ru/proxy-checker/index.php
<!– range is around 200 to 230 and 23 to 91 –> Pretty sure it's only referring to the first set of numbers, so 210.xxx.xx.xxx, or 45.xx.xxx.xxx should be allowed as being within the pre set range, IF the proxy works, and doesn't redirect you to another IP outside that range.
On checking it seems only the first set of numbers in the IP matter, and most of the ones in the challenge whitelist start in the 200 to 217 range, so look for one starting with that