Hi Russ,

we tried to reproduce this issue with the most current version (1.4) on WSS 3.0 SP 2 but could not observe those effects you experienced.

We customized a standard Document Library, adding some custom Views, exported to STP and created one new Document Library from that template before deploying UploadZen, and another one right after deployment.

After installing UploadZen, the out-of-the-box "Upload Multiple Documents" menu item disappeared and was replaced by UploadZen's "Upload Multiple Files" menu item (notice the slightly different wording, making it easy to tell the two apart) --- in all three document libraries. Likewise, after uninstalling UploadZen its menu item disappeared and the original out-of-the-box menu item re-appeared --- again, in all three document libraries with no differences in behaviour, whether based on that template or not. We repeated that installation-uninstallation-cycle once more just to be sure, but again, the effects you described could simply not be reproduced.

Are there any other menu modifications happening on your pages, i.e. by custom code or other third-party extensions?

Yes, that would be it.

Basically ListViewWebParts dynamically build their menus using files located in 12\template\controltemplates, plus depending on List and/or other other configuration.

Unfortunately, it seems like converting it to a DataViewWebPart captures the currently dynamically built structures and stores it statically in the DVWP's XSL source code. That confirms other previously seen effects such as the conversion taking dynamically resolved localized user interface text resources and storing them statically in DVWP XSL etc.

Since you rely on customized DVWPs whose XSL can be further customized, maybe it helps that you can build your own link to the UploadZen uploader Windows application, using HTML standard link-building syntax i.e. Upload Multiple Files — see more details on how to link manually to UploadZen here.