It is a clean install.
The only services I cannot stop are: 1) Windows Management Instrumentation Driver Extensions, 2) Security Accounts Manager, 3) Remote Procedure Call, 4) Plug and Play, and 5) Event Log. Attempts to stop number 1 above produce a dialog box which says, "Could not stop the Windows Management Instrumentation Driver Extensions service on Local Computer. The service did not return an error. This could be an internal Windows error or an internal service error. If the problem persists, contact your system administrator." All other services listed above do not offer the stop option using the context menu popup (right mouse button on highlighted service). Are you aware of any of these services that use MDAC?
Update: After all this, I ran the installation again. It appears from the sqlstp.log file that the installation bailed during the following:
08:28:45 Enabled CORECOMPONENTHANDLING
08:28:45 ComponentMoveData exit code: -623
08:28:56 Setup cannot continue because a file that needs to be copied is currently in use. Shut down other active processes. This error can also occur if virus-checking program is being used.
08:28:56 Action CleanUpInstall:
08:28:56 StatsGenerate returned: 2
08:28:56 StatsGenerate (0x0,0x1,0xf0000000,0x200,1033,303,0x0,0x1,0,0,0
08:28:56 StatsGenerate -1,Administrator)
08:28:56 Installation Failed.
The last thing the installer was attempting was HTML Help.
I can't seem to find the file that it claims is currently in use!