Thanks, I will try to call them and do it next week.
I have searched a lot about the subject and I found some informations :
* for some users webgl is the reason
* for some others by putting never to screen sleep the problem seems to disappear
If you have the same problem try this to see if this happen (happen a few times for me) :
Go to Gmail with Chrome and open a new tab
Expand the brower to the left or right
Go back to Gmail and it will resize automatically to the new width
Sometimes during this process, the issue appear.