Xmuxer Pro: 4GB-limit ??

hi there.
at first i wanna congratulate yo guys for the excellent H.264-codec.
the compression/filesize to image-quality ratio is much better than the x264 freeware stuff.

now to my problem:
if i'm transcoding a captured DVB-S2 h264-ts stream with ac3-tracks into mp4-ES and aac-ES with ConverterStudio and wanna mux this with XmuxerPro into mp4 all's fine.

But after muxing this created new 4.37GB-mp4 isnt playable at all, independent of the player-soft.
if i wanna load the same file into xmuxer again theres appearing a notice: file may be corrupted or unsupported format.
xmuxer dont recognice his own files ??
muxing same files into a .mkv-container with mkvmerge is working well.

another phenomenon:
if i rename the .mp4-ES into .h264 and mux it with the aac-tracks all sems to be right. But the xmuxer is muxing now exactly 4GB only and the file is not playable too.
4GB-limits are remnants of the Stone Age i thought...?!
or i'm doing something wrong ? please help.

aah, no to forget... test to mux it into .ts again takes nearly 10 hours for 4.37GB...(speed calculated, not really tested...dont have the patience.)
that isnt true, yea ?? bye...