It's normally possible to uninstall the components that will uninstall, ignore the ones that won't, then perform the named folder removals, reboot, and reinstall.
Alternatively, if you still get that message when attempting to install then there may be a registry key that needs removing. I found references to the file at:
HKEY_CLASSES_ROOT\Installer\Products\477BAEFBCD7C23040BA5ADF5C77B3B56\SourceList and
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products\477BAEFBCD7C23040BA5ADF5C 77B3B56\SourceList
I suspect deleting the branch:
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products\477BAEFBCD7C23040BA5ADF5C 77B3B56
should resolve the cannot locate .msi issue. The first instance should be a mirror of the second so only one should need to be deleted.
Of course it is possible that with a different builds the key has a slightly different path so you may need to search. Also ignore the spaces formed because the forum software breaks up any string over 80 characters that doesn't have a space in it.
tt2