Do you experience problems during downloading?
Check your connection in Status and Interface settings window.
Use Test Server in Config > Servers.
We will probably ask you to do a test using only basic settings.
Do you experience problems during repair or unpacking?
Enable +Debug logging in the Status and Interface settings window and share the relevant parts of the log here using [ code ] sections.
Full Unicode will always be an issue, because SABnzbd uses a command line interface.
Possibly it may work on OSX and Linux, but on Windows it's unlikely.