Why oversaturated blue pixels show black in PS CS5.5.?

[hebe]

When I open an oversaturated RGB image, the most oversaturated blue pixels appear as black. In Preview window the image seems normal.



It started when I changed my CS3 to CS5.5, in both 32 bit and 64 bit PS. And it happens in both 8 bit/channel and 16 bit/channel mode.

When I convert the image to 32 bit/channel, the black colour dissappears. And also when I convert it to cmyk.

Gamut Warning color is gray, and it is not turned on.

Some kind of warning? Where can I turn it off?

Regards
Heikki

 

[hebe]

Okay, I got a hint from another discussion.
I upgreded the driver for my display adapter (AMD Radeon HD 7800 series).
It helped.