Are you using a lens hood. These cameras really need the hood when shooting towards the sun. I had a ML that exhibited the same issue and knew anotehr with an ML with the same thing. The dealer where I got the Minox advised me of this when I bought it. There is almost no hood on the lens. As for the softness, I suspect the front element needs to be adjusted. The lense is a good design and sharp but the front element is a might fragile as it turns for focusing. I've seen a few where the front element would just turn 360 drgrees. It is held on with tiny set screws from memory. A tech should be able to reset the front and lock it down.
The camera is great but, does require a bit of light handed use. It is more rugged than it feels but will not take a beating and keep on ticking like bigger brothers.