Liquify depends on being able to run programs in your GPU to provide smooth service. Are your display drivers up to date?
Haven't seen an inability to use keyboard commands myself. When you get a case where it doesn't work, look closely at the Photoshop menus... Are there any letters underlined? If so, try pressing and releasing the Alt key once and see if operation is restored. I'm not saying that having the menu accelerator keys showing/enabled blocks keyboard access for me, but I wonder whether maybe some keyboard drivers or UI-augmenting software might cause that situation to be handed differently.
Item 3 sounds like a display driver problem as well.
I don't use Lightroom so I can't comment on your last point, but you certainly shouldn't have to reinstall your software regularly.
-Noel