When testing the affected sites, what errors are logged by Apache?
The following command may help by monitoring the Apache error_log while testing the web sites involved:
Code:
# tail -fvn0 /usr/local/apache/logs/error_log
While the above command will monitor just the error_log, if you wanted, you could revise it to monitor a few more like the following example:
Code:
# tail -fvn0 /usr/local/apache/logs/*log