I noticed that you already posted your question on several message boards.
The answer to your question depends on a number of factors, including the
versions of Perl and mod_perl you are using, the Perl modules referenced by the
scripts that cause the errors, whether you're using embedded Perl, etc.
The most recommended solution is installing the latest versions of Perl and
mod_perl that probably have the patches for these often discussed problems.
Other solutions include not using certain Perl modules, such as
Apache::StatINC, changing certain Apache directives, such as PerlFreshRestart,
For many specific solutions that may work for your particular configuration,
have a look at the unreferenced scalar threads on the GeoCrawler mod_perl board:
and the segmentation fault threads on Mathforum's mod_perl mailing list archive:
Also, do report your problem to the mod_perl developers. Stas Bekman, one of
the most active developers, already recommended that you do that in his reply
and provided a link to the document on reporting mod_perl problems:
More useful links:
Perldiag: Perl diagnostics (section on the unreferenced scalar error)
mod_perl Guide (sections on errors and warnings)
mod_perl FAQ (section on errors)
Doug Sparling's mod_perl links collection
Useful Google searches:
"attempt to free unreferenced scalar" mod_perl OR modperl
"segmentation fault" OR segfault OR segfaults OR segv "exit signal" mod_perl OR