Screen turns off when switching to AC-power in Windows 8

Hi

I recently decided to install Windows on my Macbook Pro 13" (ultimo 2011) and used the Bootcamp Assistant in OS X Yosemite 10.10.3 to prepare support software and partitioning.

After installing Windows 8.1 Pro 64-bit and the Bootcamp support software and drivers I ran the normal procedure for updating Windows and the included Apple Bootcamp software.

After updating all software packages I unplugged the AC-power and the screen turned off for a one second and then turned on again.If I plug in the AC-power again it turns off the screen and turns it on again after one second. This behaviour only occurrs in Windows and not in OS X.

Another issue I have in Windows is that sometimes when booting into Windows the screen turns off at the log in screen and the only way to get it back on again is to close the lid and wait for it to go to sleep and then wake it again. This sometimes also happens when being hooked up to an external display via Apples Mini-DP to VGA adapter and running in Extended Desktop mode.

I have not updated any drivers in Windows as I do not know if Apple is shipping special drivers for graphics.

The issue with the screen turning off and then coming back on is something that my old HP laptop did as it was using swtichable graphics, but since the 13" Macbook Pro does not have switchable graphics it should not turn the screen on/off when plugging into AC-power.

Does anyone have a solution for these issues?

Btw. my bootcamp version is 5.1