Connector/Net 6.5.4 installation failure (no replies)

Today I attempted to install the MySQL Connector/Net 6.5.4 and failed. The installer's MSI log is quite short:

A previous version of Connector/Net 6.3 or higher is already installed. Please uninstall that version first.
=== Logging stopped: 5/16/2012 16:34:49 ===

Having read through the extensive history in this forum for mysterious installation failures, I have checked a few things:
* There are no other Connector/Nets installed.
* "C:\Program Files (x86)\MySQL" has folders for Connector/ODBC 5.1 and MySQL Workbench 5.2 (both successfully installed today).
* Add/Remove Programs lists zero Connector/Net instances.
* msiinv.exe lists zero Connector/Net instances.
* The GAC has no MySQL.*.
* The registry only has "MySQL" in entries for Connector/ODBC 5.1 and MySQL Workbench 5.2.
* Installation and removal of the prior version (6.2.3) has not altered the 6.5.4 installer's behaviour.
* VS2010 does not list a referenceable MySQL.Data.
* No file named MySQL.Data* exists on the system drive.

So I'm stalled. How do I get a working Connector/Net?