Updated to 0.18.6 and there is no sound for notifications, installed 0.18.5 back and there is sound again.
btw Windows 7 system(can't edit post above)
Portable? You have downloaded from this site? Or updated via the application itself?
Not portable. Downloaded from site.
Send files debug.log and quiterss.ini (0.18.6)
Updated to 0.18.6 again and there is sound now... Dunno what was wrong before. Now so far so good.