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.
SABnzbd 070 b6 shows sometimes for multiple files the status as Verifying and failed. See the screenshot below. Also the queue shows multiple files that are already downloaded.
I use Windows XP