Broken sound and muffled voices - Help?

Okay, I have been working on recording my own Utau (I'm not done but I'm getting closer).
And I have noticed that something is wrong with the notes, sometimes they sounds broken (like bzzzzzzz) and sometimes they become quiter or muffled.
This doesn't seem to be anything with the oto (tho I'm not sure) because I can put a line with 5 notes of "a" and just some of them becomes broken or muffled.

Any help or tip how to fix this, please?

In English locale sometimes the resampler.dll likes to not work properly with some notes.

Check this post for a temporary solution:
https://overseasutau.forumotion.net/questions-and-tech-support-f32/utau-is-quite-moody-t2400.htm