Mouse cursor disappears in Web Player

I have a custom texture set to the mouse cursor, which functions as a crosshairs in a 2D shooter. The problem is that in the web player (not anywhere else) the cursor disappears whenever a key is pressed. It reappears if I move the mouse again. Does anyone know why this might be happening? Its hard to debug since it doesnt happen in Unity itself.

EDIT: I'm using Unity 4.6 beta (17), and I'm setting the mouse cursor with

 Cursor.SetCursor(crosshairs, new Vector2(8, 8), CursorMode.Auto);