Can you give us the operating system version?
Also, if your operating system is 32 bit or 64 bit.
What current drivers are you running on your computer?
I've found that the problem is related with the save energy settings of Lenovo's PC.
With the standard save energy settings the brightness slow down and lead to visualization problems.
Setting the Lenovo power manager in a High Permormance mode solve the problem.
No monitor or windows OS settings are efficacious.
The OS is windows 7 64 bit with last Intel 4600 HD Graphic Driver installed.