Smplayer 0.6.6 (SVN r2599)
video format: avc1 (.mp4 container)
subtitle format: .ass
Subtitles make a flash before disappear from the screen. Problem only appears with this video format, i've checked the same subs with another video (DX50, .avi container) and everything was alright. Also, there is no such problem while playing video with "pure" mplayer. When i uncheck "Use ASS/SSA library" flashing dissapears but subs lose all design and styles.