Categories are not shown anymore

[webbie65]

Hello, after migration from joomla 1.5 to joomla 2.5 i installed the categorie modul and wanted to display the categories, but it does not work!
First seems anything allright, but a view days later i have no content anymore in it. Everything is empty. I have the first categories, but when i click them,
i get an "404 - not found" error. I didnt change anything and also i did not delate anything.

Maybe someone has an answer for me?!

If someone wants to have a look at the side, please look here:
http://www.webbiene.de/off-road-center/

[webbie65]

ok, problem is solved, i had sef , when i put it back to no search engine freindly urls, averything works fine, again,