USB Connection Issues

Question

I have a SanMax HD-338-CB USB/Firewire External HD with a 160MB drive.Sometimes I have to reboot Windows XP pro 2 or 3 time before I see the drive using a USB 2.0 connection.I do not have this issue using the firewire connections.I don?t know if I have a problem with the SanMax or if it?s operator problems.Also, how large of a HD can be used and are firmware updates available.Thanks,Cat