When trying to do an apt-get upgrade the MySQL package failed with the error message:
package mysql-server-5.1 5.1.37-1ubuntu5.1 failed to install/upgrade: subprocess new pre-removal script returned error exit status 1
The problem is that the start / stop script for MySQL fails to stop the running MySQL server before upgrade.
apt-get update ps ax | grep mysql
Now kill each process that has to do with MySQL.
Voila – now it works and MySQL gets upgraded.