Running the control panel - system administration - font installer as admin. Exit and restart the x session.
Check your fonts are anit-aliased in control panel - appearance and themes - fonts. Check too that no fonts are excluded when you click on the configure.
Thanks for help, I have tried it. Nevertheless, after clicking on the Font Installer button I got an error message: -------------------- There was an error loading the module. Details: The diagnostics is: Library files for "libkcm_fontinst.la" not found in paths Possible reasons: o An error occurred during your last KDE upgrade leaving an orphaned control module o You have old third party modules lying around. Check these points carefully and try to remove the module mentioned in the error message. If this fails, consider contacting your distributor or packager. -------------------- Does anyone know what shall I do? Or how can I fix this problem?