Issue on DP-Monitor after driver upgrade from 16.4



i am stuck on a quite old driver version. If i try to upgrade to a newer driver, i have issues with my main monitor. Randomly, there are some thin, white stripes and sometimes, the whole monitor gets black. The desktop remains visible and usable, but that is extremely annoying. 


This issue does not occur on my 2nd monitor, which is connected with DVI.


Information about my stuff:

Sapphire HD 7850 2GB

DELL U2412M (1920 x 1200, connected with Display Port)

DELL whatever with 22" (1680 x 1050), connected with DVI.

2500K, MSI P67A-GD53, 500W Straight Power E10, Windows 7 x64


Does anyone know something i could try? Hope it can be fixed somehow - tried later drivers for months and i always had to rollback.