Just tested here with a fresh install of 0.25.0 on XP, and everything's working fine: entry appears on par2 tab with Unrar icon visible, downloads and unrars no problem.
So either you need to check your settings again, try different NZBs, try re-installing (copy altbinz.exe to new folder and launch from there), or find out what's changed on your system that may be interfering with Alt.Binz.