[zealous]

Hmm. I've never encountered a problem like this. If worse comes to worse ,
Go to run , type in regedit and click ok.
Then , on your left , expand until you find HKEY_LOCAL_MACHINE\SOFTWARE\BlueStacks\Guests\Android\FrameBuffer\0
(left click on the 0)
You should see this

Now double click on the attributes and change them according to the value above. (Remember to change it to the decimals)

Then Save and exit and restart your computer and it should work
Hope i helped