Shouldn't be a problem.
Perhaps try "Draw subtitles to Overlay surface" under:
(rightclick >) Options > Preferences > Subtitles > [Subtitle properties] ?
You could also try a different "Rendering mode" (overlay) under
(rightclick >) Options > Preferences > Video > [Video rendering] ?
Further maybe read
this post (click here) and item
(9) of my
Help2Help-post.