Well, have no doubt that sound blaster drivers are crappy lately, but got my reasons to think it's not their fault this time, as I've proved 2.79 in another computers with different sound card makes (mine is a SB 128, others are a Guillemot one and a SB 16), under different OS (Win 98 1st ed., XP and Me) and in my case with different driver sets. It only happens with this version of winamp and with this particular dll. As I said waweOut works fine, 3rd party Dsound crossfaders work fine, and old DSound dll works fine.
No cuts or so, it just starts playing the song following the one I double-click, and only the FIRST time i click one, just after opening winamp. If I spend some time messing with menus before playing a song it doesn't happen. If I open it by hitting the play button instead of double-clicking the playlist, it doesn't happen. if i open it by clicking a mp3 or m3u file, it doesn't happen, and so on. This and the fact that the Dsound dll has been remodelized makes me think it's an error in dsound module.
And only saying it because I have noted it and I think it's a dumb error that has slipped and I think the solution will be easy. It doesn't disturb me, as I can use Waveout, or my old 3rd party Dsound plugin.