Progressive desync with dvobsub?

[Bulletproof]

I sent a video and SSA file to a friend and had them install vobsub 2.18, it seems the subtitles do not sync up, yet it works perfectly fine on my machine and another friends machine? So two of us can get it to work, and another two get a progressive desync. And it's not their CPU power. What could it be?

[Yusaku]

it probably indeed IS CPU power - check that he has "prebuffer subpictures" checked in settings - that is the most common reason (sometimes even on 2GHz machines!)