I have this problem occasionally. I use subtitle workshop to fix many subtitles but have never solved this issue. It usually occurs with only an older movie. I can get the subtitle perfect when adjusting the time whether by frames or time to show the first subtitle exactly in sync and the last exactly in sync. Somewhere in-between the subtitles will be out of sync by one to several seconds or more off. It can be anywhere at 1/3 of the move to 2/3 of the movie where they stray off. Strange they can be perfect at the beginning or end. Even when using Gspot to identify the frame rate of the movie and changing accordingly I still can never fix this problem. I have tried downloading many subtitles of the same movie and still never been able to sync completely on some movies. Very annoying to say the least. Somehow there has to be spacing added or deleted between text to fix this, never figured it out. Any help highly appreciated as I do not hear well and totally rely on subtitles, yet can lip sync enough to see when they are off which drives a person crazy.