....If you remembered to disable automatic Windows Updates [Windows Update | Change settings | Important updates | Never check for updates (not recommended)] and re-boot before running your manual Windows Update and it still hangs for hours on "Checking for updates..." then re-read my comments in post # 8. At this point I still think your best option would be to avoid using Windows Update altogether and use the WSUS Offline Update tool to patch your system as I suggested <here>...
Just a warning to users following this thread that Torsten Wittrock's WSUS Offline Update tool v10.9.2 was the last version to support Vista SP2. The change log for the current v11.0.0 (released 28-Jun-2017) at http://download.wsusoffline.net/ states "Support removed for Windows Vista since Microsoft discontinued support for it on April 11, 2017".
32-bit Vista Home Premium SP2 * Firefox ESR v52.2.1 * NS Premium v220.127.116.11 * MBAM Premium v3.1.2