SQL server install error:One or more of the components being installed are already registered as 32 bit components in the target application.

Recently I got this error while installing SQL Server 2005 64 bit on a machine where previously SQL Server 2005 32 bit was installed:

Failed to install and configure assemblies C:\Program Files\Microsoft SQL Server\90\DTS\Tasks\Microsoft.SqlServer.MSMQTask.dll in the COM+ catalog. Error: -xxxxx
Error message: Unknown error xxxx
Error description: One or more of the components being installed are already
registered as 32 bit components in the target application. You must install
the 64 bit versions of the components being installed in a different COM+
application, or delete the existing 32 bit versions of the components being
installed from the target COM+ application prior to attempting install of the
64 bit versions. COM+ applications cannot contain bit neutral components.

Since the MSMQTask.dll was already registered as a 32-bit COM+ component with the host Windows machine, the solution is to simplyunregister it as follows:

Go to:

Administrative Tools->Component Services->Console Root\Component Services\Computers\My Computer\COM+ Applications

and then delete  the Microsoft.SqlServer.MSMQTask component.

Then click Re-try in the SQL installer and it should work fine.