We're running ZC 1.3.9H with user tracking with no problems. Cart contents don't show but am working on that. will post back if and when I have an answer.

Some of these issues you guys are having sound like there is likely a conflict with one or more mods you have installed.

You should carefully read through each mods readme to see which core files may need to be merged with other core files you may have overridden previously.