MP4box interleaving problem

Hi there
I have used this tool a few times now very successfully.
However i am getting an error at the end of the conversion where it joins the split files together to create the final mp4 file.
The final interleaving process crashes and leaves a file called Hangover.mp4 however the file is 0 bytes.

This does not happen if i choose to split the file (its over 4gb)
However i do not want to split the file.

Its not a file name problem the file i am converting is D:\Done\Hangover.mkv
The temp dir is D:\Done\Temp

See logs below.
As you can see it does not do the interleaving part of the conversion

Please help me

[13/12/2009 15:01] No scratch folder set. Temporary files will be stored in D:\Done\temp\. Use Tools/Options to change.
[13/12/2009 15:01] Processing file: D:\Done\Hangover.mkv.
[13/12/2009 15:01] Starting conversion process for D:\Done\Hangover.mkv.
[13/12/2009 15:01] Checking whether the MKV file needs to be split.
[13/12/2009 15:01] Hangover.mkv will not be split due to user preference.
[13/12/2009 15:01] Retrieving MKV information.
[13/12/2009 15:01] Length of MKV file is ~6474 seconds.
[13/12/2009 15:01] Detected video or audio codec: V_MPEG4/ISO/AVC.
[13/12/2009 15:01] Video dimensions (width x height) are 1280 x 536.
[13/12/2009 15:01] Video display aspect ratio (DAR) is 2.35.
[13/12/2009 15:01] Rounding up the pixel aspect ratio from 63:64 to 1:1.
[13/12/2009 15:01] Video pixel aspect ratio (PAR) is 1:1.
[13/12/2009 15:01] Detected video or audio codec: A_AC3.
[13/12/2009 15:01] All tracks from MKV file were detected.
[13/12/2009 15:01] Automatically selecting video and audio tracks from the MKV file.
[13/12/2009 15:01] Using track 1 (.h264) for video and track 2 (.ac3) for audio.
[13/12/2009 15:01] [W]Demuxing the MKV file into video and audio tracks.
[13/12/2009 15:08] [A]Changed video bit from AVC 5.1 profile to AVC 4.1 profile.
[13/12/2009 15:08] [W]Starting Azid AC3 decoder to create a WAV file.
[13/12/2009 15:15] Initializing Nero AAC encoder with quality parameters: -q 0.5
[13/12/2009 15:15] [W]Using Nero to convert WAV to 2-channel AAC. (This might take a while to get started.)
[13/12/2009 15:20] [W]Generating MP4 file from x264 video and 2-channel AAC.
[13/12/2009 15:20] [W]Using mp4box version 0.4.6-dev (default, February 2009) to generate file.
[13/12/2009 15:29] [A]Conversion complete.

AVC-H264 import - frame size 1280 x 536 at 23.976 FPS
Importing AVC-H264: | | (01/100)
***
Importing AVC-H264: |=================== | (99/100)

Import results: 155208 samples - Slices: 1841 I 68709 P 84658 B - 1 SEI - 1785 IDR
IsoMedia import - track ID 1 - Audio (SR 48000 - 2 channels)
Importing ISO File: | | (01/100)
***
Importing ISO File: |=================== | (98/100)
Importing ISO File: |=================== | (99/100)

Log ends here