I have just installed XAMPP on my Windows XP machine, and I get an error saying:
Connection for controluser as defined in your configuration failed.>
On Ubunbtu.
Ben's message is close but it's not the root password that is the problem, the problem I found was I had created a password for the phpmyadmin database when I installed it. This password is not carried into the installation on ubuntu so the variable $dbpass=''; in the database settings file is empty and not the password you set.