agree for the "DIRECT STREAM COPY" mode for both audio & video ; that was your problem.
Adding, to avoid some possible audio time lag in the cutted part, that you can reencode audio of the original, from VBR to CBR, then cut your part after.
[and remember to always be on a keyframe for the beginning ; not necessary for the end]

cheers

• Cutting a movie in smaller parts - Rover 23:31:55 08/28/2008 (9)
  • VirtualDub 1.8.6 is out - Rex 03:23:29 09/22/2008
  • Re: Cutting a movie in smaller parts - Uncle Bill 23:37:15 08/28/2008
    • nm: Thx, Uncle Bill, I'll do as suggested - Rover 03:05:53 08/29/2008
      • I will point out what was up with VD... - s_4me 09:02:40 08/29/2008
        • ^^ good process with VDub - faust 12:13:24 08/29/2008
          • Thx Smiley and Faust .... inside pls - Rover 15:15:28 08/29/2008
            • nm: Smiley, testing results, my learnind curve - Anonymous 15:16:54 08/30/2008
              • You can do most anything with VD - me 01:51:00 09/18/2008
                • nm: Thx, Me, for your help, cheers - Rover 04:45:00 09/20/2008