I have a Viewsonic VP201b monitor connected via DVI to my MBP. I have no issues with using the screens whether mirroring is on or not but if the MBP goes to sleep I find that when I wake it the external monitor will not wake. I am as updated as possible at the moment. I also disabled the ambient light control for the lcd thinking it might be something there but to no avail. I have found the only way to get the external back on is to unplug the power cable and then plug it in again. I have never had and issue with this monitor until this MBP. Any advice is appreciated.