I had the same exact problem. I have Windows ME and ZoneAlarm, and it locked up on me every time. I uninstalled Zonealarm using the uninstall in the program folder, then I went to the site (where it instructed me how to remove some system files that are removed in the uninstallation). I then downloaded the Sygate firewall, and now Xolox works perfectly! Haven't had a problem with it since. Not sure if it's some combination of Windows ME and Zonealarm or something else. I know someone else who had Windows 98 and Zonealarm and didn't have any problems running Xolox.