The Vista Update Search issue gets triggered by applicability of at least one of the following updates for a given installation: KB4015195, KB3191203, KB3185911, KB3087039, the Cumulative Security Update for IE9, Excel and Word related Security Updates for Compatibility Pack SP3, Office 2007 and Office 2010.
An installation can be made ineligible for the issue by manually preinstalling all applicable of the following:
KB3164033, KB3140735 and KB3087039)
KB3191830 (Compatibility Pack SP3) Download
KB3178682 (Compatibility Pack SP3) Download
KB3191827 (Excel 2007) Download
KB3178683 (Word 2007) Download
Set automatic updates to "Never check for updates" and reboot prior to manual installation.
Here are the March 2017 Vista Update download links.
If I missed one, please advise. IE9 is included above.
Vista Support ends April 11, 2017 per MS here.
EDIT - If you have Microsoft Office, find your March 2017 Version Updates here. I have Office 2007 - still supported.