[Typo3] the page is not configured error

["Prágai, Róbert"]

Hi!

	First of all, I am a newbie in Typo3 and want to say thank you for all for this
great project.

	Next, my question is: I played around with the quickstart tutorial and after
inserting the newsletter extension I ran into an error. Using the "View" menu
all the pages show the next error message:

	Error! The page is not configured! [type=1][]

	Moreover on the frontend every pages seem to be blank.

	How can I fix this and what could possibly cause this effect?

thanks in advance,
Robert