Apple Mac having issue connecting to secure sites through wireless connection

I have a customer who just added a metro wireless connection to his office in Los Angeles and is seeing speeds at 10M down and 3M or so up for all machines on the network (30). His Apple Macs, however can not do anything with secured sites such as Paypal or Bank of America etc when accessing them, they just hang. The MACs have no trouble with the same sites when the machines are on a regular DSL or T-1. I am having him put a tap on the host first and then capture the info with WS on his other Windows laptop. What should I be looking for when we start hunting?> MAC OS = 10.39 Thanks Eric