problem solved – i just installed everything new. thank you, nevertheless
yes, that is true.
well, i installed a new theme (de-po clean theme) and changed a little bit at the css. but that’s it, as far as i remember.
no new plugins installed (i had the following plugins installed: flickrRSS, feedburnerstats and snapshots).
i also did not change the .htaccess file on purpose. i have a previous backup-version of the blog on my harddisc. is it possible only to replace the .htaaccess?