The reinstall (at default settings) overwrites the currupted installation and plants the uninstall in correct location. I found a solution but not the cause. The reason for removing was I ran Win Experience Index before and after updating my Intel Graphics driver to latest available driver and found my values actualy decreased with the new driver. I assume my Acer Aspire E1-571 has customised graphics drivers which of course are years old! The update utility did not degrade performance but was unnecessary.
As usual Boggin, thanks for being the first responder.