Length/skip problem remuxing PAL DVD

Hi folks,
I demuxed a PAL DVD using ifoedit (also tried rejig) in order to add subtitles (correct length, synced to an original subtitle and syncs perfectly with film).
When demuxed, the resulting .m2v video file plays smoothly by itself, however when remuxing the files using both ifoedit or rejig, the time length in the resulting ifo file is wrong, it shows about 1 hour too long. Also, the resulting vobs skip intermittently, I believe the problems are related. Can someone help pls, did this n00b miss something obvious?