I called the Adobe helpline and 13p a minute and £1 later I spoke to a person who agreed to call me back in 30mins. 2 hours later nothing but a post from someone on the Adobe forum did help and I uninstalled, rebooted and reinstalled the C++ redistributable x86 and x64 versions and finally working Lightroom.
To be fair it was not a bad two hours, my son and I made slime with a reasonable degree of success, from https://theimaginationtree.com/easy-uk-slime-recipe-contact-lens-solution/ .
Our only mods were that we had to experiment with the contact lens solution (Superdrug, it's £10 for a large bottle!) and our best result so far was with around 4ml of it (we used those little baking spoons with markings for ml and proportion of teaspoons on them to be more accurate) - it's pretty running but doesn't snap. I also found a nicer feel by mixing the bicarbonate of soda with a tiny amount of hot water to melt it first.
Last comment - I thought I used a lot of glitter, it needs a lot of glitter - I suspect the whole tube I had would still be insufficient.
Update .. that solved the Genie Timeline issue too it seems (the reinstall not the slime)