Opening Office 2007 files using Office 2003 with Office 2007 Compatibility Pack

Our Citrix server is old and running Windows 2000 Server.  With that, the most current version of Office that can be installed is version 2003.

We have installed the Compatibility pack for Office 2007 files, however recently, we are unable to open any Office 2007 documents.

Aside from the obvious solution to upgrade the server and software, I am trying to see how we can get these files opened, since we should be able to with the Office 2007 Compatibility Pack.

I have downloaded and installed the latest one, did all Microsoft updates, so I am at a loss of what to try next.

When I double click a DOCX file, for example, it attempts to convert for several seconds, then a pop up appears stating, "There was an error opening the file."

When doing a File, Open, I am prompted with the same message.

This happens for all documents and spreadsheets that I've tested.  It worked in the past, but I believe a Microsoft update or some other change is now causing this functionality to no longer work.

I have rebooted and the problem persists.

I have also uninstalled the Compatibility Pack, rebooted, and reinstalled it.