Converting a single line of text to curves goes fine as long as the text is not placed on a circle.
However, if you select 'several lines' with the command text (tools -> text), and you place some lines of text, you are not able to convert text to curves anymore.
Unless you first explode the text into single lines.
I think that's not logical. Text block or not, when I give the command convert text to curves I want it to convert whether it is a block of text or a single line.
The best way to convert text block to curves is to explode the textblock with explode (to be found at the edit menu).
After that you can convert the text as normal.