Sharepoint Document Library custom Document Template will not delete and/or will not "take" updates

I have a Sharepoint document library which I need to change the template for monthly.  Rather than overwrite "template.xlsx" each time, I've named it Spreadsheet 2010-06.xlsx based on the month.

When I've edited the actual template through the Advanced Settings window and saved it, the updated version doesn't consistently "stick."  Same thing for overwriting the file with a version from my desktop.  Inconsistent.

Additionally, when I actually delete the document template from the Forms folder in Explorer View, it restores itself.

In this library:

1. Content Approval is required
2. Major Versions are created
3. Users can see only their own documents
4. Documents are not required to be checked out before they can be edited

Are my issues related to versioning or content approval?  Does the admin need to change the caching settings on the server for this subsite?  Is there a patch?

We are running SP 2007.

Thanks in advance!