Blocks

I am using Moodle 1.5.3+ (the newest one)
I am using sl_utf8 encoding on my moodle,
for locale of calander i am using sl_SI, and all write right for calander,
but in courses, when i want to see activities, is one of the in day-> Thursday in slovenian called Četrtek (c with carrot) and it doesn write that c with carrot it show <?> unknown character, but if i change encoding in browser to Windows-1250 those č are working but al others don't. If all is set to sl_utf8 everywhere works all characters only here is courses is problem.
So how can i solve this, where could i set php code for that character?
Tnx
Din