three comments:
1) please always copy the mailing list on your replies.
2) the log file does not agree with the section of the data file that
you copied (+/-50 vs. +/-20 for box dimensions)
3) the box dimensions are given as floating point numbers, so they
*cannot* trigger this error.
the error is likely caused by an invalid atom id somewhere or by a
violation of the expected data file format
axel.