You probably downloaded the trial of the Created Cloud version of Lightroom and your Perpetual version License key will not work. Uninistall the existing version on your laptop and download from the link below, install and your license key should work fine. The uninstall process will only remove the Lightroom Application file and not interfere with your Catalog, Preferences or personal files.
LR was loaded in each case from an ADOBE purchased DVD, not downloaded. The skies are clear, no Cloud is involved and there is nothing to uninstall.
Most likely system problem. Same problem trying to load update to Google Sketchup, plus a few little things not right. Will backup and re-install OS and try again