Fix Version/s: None
ros 0.4.6RC1 tested here.
VBox4.3.12 + VBEMP + inbuilt Mesa + AC97 from rapps
I used no VBox 3D acceleration driver
It happens right before I play a video file:
I tested the same file multiple times in the past with MPC HC 1.7.10 against older ros releases and did not get that box. Now MPC HC 1.7.13 shows it. So either a new regression on our side or unhidden by latest MPC version update.
Since the message-box can be continued and the video still plays afterwards, I rate this only 'trivial'.