I have many years of experience troubleshooting code, database and server problems. I have worked on many sites. Sometimes the problem is caused by the host changing something on the server, or a web developer makes a change without testing it first or sometimes a web site gets too many visitors and the server can't handle the increased traffic. I've seen and dealt with all of these.
I have worked with PHP since 2001. Before that I worked three years doing CGI programming with Perl and C. After a lay off in 2000 I began freelancing and learned about PHP.
As PHP has evolved so have the projects I've worked on. A few years ago I reviewed a number of the MVC frameworks: Zend Framework, Symfony, CodeIgnitor, CakePHP, etc. I had a specific project in mind and used CodeIgniter for it. A few months later I used Zend Framework for another project.
MVC framework experience: Zend Framework 1.x, CodeIgniter, Kohana
Sybase with Perl and C
MySQL since 2002, with Perl and PHP
Others: PostgreSQL, DB2
Linux - user since the 90's; experience setting up and maintaining Linux web and database server. My personal desktop is Debian. I've also dealt with CentOS, RedHat, Ubuntu and Suse.
Windows - some experience with web sites hosted on Windows, but don't ask me to do any OS level maintenance, I can configure Apache, MySQL and PHP on Windows