I seem to recall once having some problems with a PAL to NTSC conversion with subs. Try this free app. Using HCenc it produces superior results to DVD Flick. You do need .NET installed though. http://favcfavc.googlepages.com/
I hadn't heard of FAVC before, will have to try that one; i use ConvertXtoDVD for most avi's, and for any 2part avi's with or without subs i use DVDFlick; as i use HC encoder heavily with DVD-RB i'm interested to see what FAVC/HC can do. Cheers.
Here's another HCenc ready app. http://www.videohelp.com/tools/AVStoDVD It will allow you to tweak it's Avisynth script, do some cropping, brightening, sharpening etc. before the conversion. Very handy sometimes.
