I have been through lots of forums and checked various posts on similar topic but non seems to work out for me.
I have freshly installed XAMPP 1.7.7 on my Ubuntu 11
The problem might be with service mysql-server and apache2 running while system start. You can do the following.
sudo /opt/lampp/lampp stop
To stop already running default services
sudo service apache2 stop
sudo service mysql stop
To remove the services completely, so that they won't create problem in next system-restart, If you are in ubuntu(debian)
sudo apt-get remove apache2
sudo apt-get remove mysql-server
If you are in redhat or other, You could use yum or similar command to uninstall the services
Then start the lampp again
sudo /opt/lampp/lampp start
Also, don't install mysql-server in the system, because it might start in system start-up, occupy the port, and create problem for mysql of lampp.