I'm getting those notices. Since I'm not too familiair with pHP I'm not sure what it means and how to solve. Can anybody please help?

These are the notices:

Notice [PHP]: Undefined index: query in file modules/statistics/include/hitcounter.php line 64

Notice [PHP]: Undefined index: fragment in file modules/statistics/include/hitcounter.php line 68

Notice [PHP]: Use of undefined constant _XT_TE_BLOCO - assumed '_XT_TE_BLOCO' in file modules/xt_temas/blocks/xt_temas.php line 6

Notice [PHP]: Use of undefined constant visitname - assumed 'visitname' in file modules/uservisit/index.php line 37

Notice [PHP]: Use of undefined constant temps - assumed 'temps' in file modules/uservisit/index.php line 38

Notice [PHP]: Use of undefined constant tempsf - assumed 'tempsf' in file modules/uservisit/index.php line 39

They are only notices and should not cause a problem.

They shouldn't appear unless you have debug set in the admin. If you do not have PHP debug enabled, that means your php error reporting in php.ini needs adjustment.

Otherwise:
You can turn off debug and forget you ever saw them.

You could remove them, but it would take a working knowledge of php to do so. They will in no way adversly affect your site.

Thanks Tripmon, that's what I wanted to know.