Hi,
the problem seems to be that the default X session script redirects both
standard output and standard error to .xsession-errors, when it really
should only redirect standard error.
Imagine what happens when the user runs a program such as mplayer that
writes a lot to stdout because it updates its status line several times per
second. All this data ends up in .xsession-errors, which gets very large
very quickly. This kind of output doesn't belong into a log file.
Please, consider changing the following line from the Xsession script
exec >>"$ERRFILE" 2>&1
into:
exec 2>>"$ERRFILE" >/dev/null
I think that this would fix the issue.
Regards.