I have opened the Console application to find the last error messages raised from the Apache server, and I found this entries, in the "All Messages" section (the default one selected when the Console application is open).
I would like to find what is causing the error, and avoid it is executed.
How can I find the cause of this error message, and stop it gets executed?
The error that the person gets in that question is just about the same as the one as you are asking except that his UID is 501 where yours is 32752.
The answer i believe that might solve your problem is provided by the user JasKerr:
I can answer your last question, but it will take more work to solve the problem.
The peruser indicates a launchd daemon started by a userland process. The numeric suffix is the UID. In this case, an application attempted load a launchd job as user 501. That failed, since there appears to be no user 501 on your system.
Have you installed software recently? User management utilities changed in Leopard, so an installer intended for an older version (Tiger?) may not work properly in 10.5.6.
Start by taking a look at ~/Library/LaunchAgents, /Library/LauchAgents, and /Library/LaunchDaemons. There may be a job that's UID 501.
If not, you could do a (brute-force) search for an application/file owned by 501:
sudo find /Applications -user 501 | less
If anything turns up, that will point to the culprit.