Color distorsion on a locked machine after using Cinnamon lock screen

[KAMI]

Cinnamon 2.6
Linux Mint 17.2

When I lock my laptop computer the try to unlock when the screen is turned off then I got color distorsion on Unlock screen. I tried Linux Mint provided X, Mesa and Radeon stack then swirched to utopic. Both of them suffer from this problem. This happens only 10% of cases. To workaround this problem I have to switch to text console or select swtch user and login back to the same user.

[KAMI (kami911)]

01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Seymour [Radeon HD 6400M/7400M Series]

ii xorg 1:7.7+1ubuntu8.1 amd64 X.Org X Window System
ii xorg-docs-core 1:1.7-1 all Core documentation for the X.org X Window System
ii xorg-sgml-doctools 1:1.11-1 all Common tools for building X.Org SGML documentation
ii xserver-xorg-core-lts-utopic 2:1.16.0-1ubuntu1.2~trusty2 amd64 Xorg X server - core server
ii xserver-xorg-lts-utopic 1:7.7+7ubuntu2~trusty1 amd64 X.Org X server
ii xserver-xorg-video-all-lts-utopic 1:7.7+7ubuntu2~trusty1 amd64 X.Org X server -- output driver metapackage
ii xserver-xorg-video-ati-lts-utopic 1:7.4.0-2ubuntu2~trusty1 amd64 X.Org X server -- AMD/ATI display driver wrapper
ii xserver-xorg-video-radeon-lts-utopic 1:7.4.0-2ubuntu2~trusty1 amd64 X.Org X server -- AMD/ATI Radeon display driver

ii mdm 2.0.4+rafaela amd64 MDM Display Manager
ii mint-mdm-themes 2014.10.29 all Linux Mint MDM Themes
ii mint-mdm-themes-gdm 1.8.1 all Linux Mint MDM Themes
ii mint-mdm-themes-html 2.0.3 all Linux Mint MDM Themes

HP Probook 6560b / Linux Mint 17.2 / 64 bit