CentOS 5 :: Browser Gives Error As For Non Existing Page

I've installed CentOS 5.3+ xampp 1.7.2 (apache,proftpd and php5) +postgresql 8.4. And some strange errors appear from time to time, but can't reproduce it by wish. For example client opens a webpage on CentOS, the page can be open many times, but in some moment browser gives error as for non-existing page and when I check lampp's logs, there is only a record in error_log "[notice] child pid NNNN exit signal Segmentation fault (11)".

Or another example: client opens ssh-connection and ftp-connection. When ftp-connection got timed out and server closes it, ssh-connection unexpectedly gets closed the same moment without any errors in logs. And again it happens not everytime, but cannot be related to physical network because the same server on the same network with Fedora never had such errors. Possibly xampp-1.7.2 is not too compatible with CentOS 5.3? How to get more info from system in this case?