I posted this patch to fix a problem with the Sony BDP-S370 blu-ray player, but I guess it solves a problem that could be present in other renderers, so I'll cross-post it here so that other people can benefit.
The bug occurs because some renderers expect to receive the media stream via multiple partial-content responses. PMS handles the partial responses correctly, but unfortunately it reports the content length of the response "chunks" incorrectly which causes some renderers to declare the media corrupt.
I posted the patch on the PMS bug tracker on google code under issue #822.
The patch is also available directly here.