The next step after system_setup in v1.3.x is to check whether there is a phpBB install available somewhere, and if there is, it attempts to verify its config.php settings and access its database.
So, if the "hang" you're referring to is happening after clicking to "save" your system settings, AND you have phpbb installed, try temporarily renaming your phpBB folder (to something unusual like "abcdefg") and/or its config.php file while doing your Zen Cart install. That should cause it to ignore the phpBB inspection. Naturally, undo the renaming after you've finished the zc install.
Other than that, there's nothing significant on the system_setup page to cause any freezing, in which case, as the others have said, maybe you have a bad set of files on your server?
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