I have not previously heard of this happening; the installer reads the registry to find a path written by SketchUp's installer, indicating where SketchUp was installed, and otherwise falls back to checking whether it can be found at the default install location. So I guess the first thing I would try would be to repair/reinstall SketchUp, in case the registry key has been deleted (perhaps by the use of registry-cleaning software).
hardware question :)

1) Start considering the actual hardware shortage.[…]

New podcast - CG Talks

Hey guys! We have just finished the second season[…]

So I've jumped into Maxwell again after a few year[…]

Let's talk about Maxwell 5.2

I stick to Maxwell for now only because the easy t[…]