flv conversion failed - retaining flv file....

[Rick Spurway]

Hi. I did a fresh install of the Windows version, changed the perl
file and get_iplayer is functioning fine, for example, when using....
get_iplayer --modes=best --pid=xxxxx etc. Everything downloads perfectly.

However, having done the fresh install an error has appeared during
the conversion of the file to mp4...

frame=58327 fps=1475 q=-1.0 size=  426480kB time=00:38:53.05 bitrate=1497.5kbits
frame=59379 fps=1483 q=-1.0 size=  434247kB time=00:39:35.12 bitrate=1497.8kbits
frame=62282 fps=1535 q=-1.0 size=  455442kB time=00:41:31.28 bitrate=1497.6kbits
[mp4 @ 022AB900] Application provided invalid, non monotonically increasing dts
to muxer in stream 1: 121659408 >= 120813552
av_interleaved_write_frame(): Invalid argument
INFO: Command exit code 1 (raw code = 256)
WARNING: flv conversion failed - retaining flv file
INFO: Recorded G:\iPlayer Downloads\The_White_Queen_-_Episode_1_p018sxvb_default
.partial.mp4.flv

Which application is responsible and what does anyone suggest I do?
Many thanks,
Rick