By creating a menu item in Joomla 2.5 an error may occur, if a menu item has the same "Menu Title" or "Alias"  like a other created menu item. In this case the following error appears:

Save failed with the following error: Another menu item with the same parent has this alias

A occurring error at Step 4 "Database" of Joomla 2.5 Installation is, that the server reports:

"An error occurred while trying to create the database. The user may not have enough privileges to create a database "your entered Database Name". The required database may need to be created separately before you can install Joomla!"

At the input of the basic settings at "Step 4 Database" of the Joomla 2.5 installation, it can happen, that the server reports:

"Could not connect to the database. Connector returned number: 2"