Really annoying weight painting problem

I have 2 computers, one laptop, and Desktop. Each computer has a differnt version of blender, both versions particulary new, yet I always have the same problem every time I weight paint. I paint it and the mesh does not deform with the armature:confused: , then when I try to switch bone, I get an error report, an my Blender Crashes:mad: . It’s really annoying.