CS5 is version 12, actually.
Huh, weird. It definitely DOES accept it in the field. I wonder if this is another related problem? Have you noticed any other weirdness in your computer behaviour lately? Any other little things not working that should work?
Ok, then don't worry about any other labs. You have all the evidence you need.
Now we're in "very good friend" territory. Do you have one who would let you borrow their computer screen for a day so you can attach to your computer and calibrate?
This is rather common with some screens, and it's very annoying, isn't it???? Yes, I think you've done the right thing choosing "normal".
Yes, this also seems like the right thing to do.
Can you elaborate on this? What did you try, exactly?
The only way I know is to add a blank layer then press D to make sure you have black and white swatches, then go to Filter>Render>Clouds. Then go to Image>Adjustments>Levels (not a Levels layer, actual old-fashioned destructive Levels) and press Auto to make sure it's black and white. Then change its blend mode to Screen. Then mask as desired.