weird error_log behaviour

I have a cgi running in apache, written in the c++ language.

The first thing this cgi does is try to read a file of the local fs.
If the file does not exist then it writes a error message and exits.
Now when I check the error_log, the message I am expecting is in there
but instead of being contained on one line, it is split over multiple
lines where each line contains one character from the message string.
This was not occurring before we migrated to a new linux distro. The
apache configuration file used on the previous freeBSD based server
did not have this problem.

The error is sent out of the cgi using cerr, i.e.

cerr << "Cannot read the local configuration file" << endl;

Does anyone know how to stop this behaviour? I'm more than willing to
accept that it is some configuration issue that I missed :)

I have google'd for this and found that others have seen this problem
but none of the posts I read have a solution in them :(

TIA,
Pep