No video, only audio when AVI cut (using VirtualDub, VirtualDubMod, or NanDub)

[Ez888]

I've been trying to cut an AVI file in 3. I've used Nandub, VirtualDub, and VirtualDubMod and all three have given the same result. I assume then that the problem must be mine.

When I cut, the first segment (from time 0 to 1/3) comes out fine, with video and audio. Any other segments (the 2nd and 3rd) that I try to cut end up with audio but NO VIDEO! The original file has both audio and video for its entire duration. Can somebody help me resolve this problem?

The file info is as follows:
VIDEO STREAM
Frame size, fps (us per frame): 432x240, 29.970 fps (33367 us)
Length: 211920 frames (1:57:51.07)
Decompressor: DivX 5.1.1 Codec
Number of key frames: 2090
Min/avg/max/total key frame size: 1166/5665/14239 (11564K)
Min/avg/max/total delta frame size: 59/3122/24107 (639778K)
Data rate: 755 kbps (0.76% overhead)

AUDIO STREAM
Sampling rate: 44100 Hz
Channels: 2 (stereo)
Sample precision: N/A
Compression: Fraunhofer IIS MPEG Layer-3 Codec
Layout: 517 chunks (0.50 preload)
Length: 84726293 samples (1:57:51.13)
Min/avg/max/total frame size: 399/410/5991 (208K)
Data rate: 96 kbps (5.52% overhead)

[setarip]

1) Load the original .AVI file (DivX-compressed or otherwise) into the most recent version of either VirtualDub or VirtualDubMod

2) Set "Video" to "Direct Stream Copy"

3) Select "Check for errors"

4) Select "Mask bad frames"

5) Save with a new filename

[Ez888]

I've checked for errors, and as far as I can tell... there aren't any. For some reason, "Mask bad frames" is greyed out for me, and I can't select it.

Any other advice?