You did not mention what kind of videocard you have and if you use Clone-mode or ...
If its a Nvidia card you could try what happens if you e.g. don't use overlay (both on BSPlayer's "Video" -tab of "Preferences" and for the video-card: right-click on an empty place of your desktop-screen, select screen properties and find your way to the advanced section ... If there is a tab for your Nvidia card, click on it. You may have to go through e.g. "Additional properties" of a tab of your card's name. There probably is an "Overlay tab", where you can select, deselect or disable overlay.
(You may try different combinations of settings and perhaps also include selection or deselection of VMR-9 (at BSPlayer's "Video"-tab) in your tests.)