XP SP2 ... I seemed to have a problem with the mail scanner at first (using Thunderbird, and it was still manually set... upon starting it, it refused connections to 127.0.0.1). Simply setting the server settings for both accounts back to normal, turning off and restarting the subsystem fixed the problem (I receive over 100 viruses a day, so it immediately passed the test as it snagged one). So far, so good.