Windows Search 4 broken by recent update causing MDAC corruption

My XP box index is complete, but Windows Search 4.0 returns nothing. The Event Viewer has no interesting Windows Search Service events; the indexer seems happy, but the search isn’t working. Rebooting didn’t help.

On any search I get "Nothing found in All Locations for query ...".

The only hints I could find wer ea recent post with a Vista problem: SearchIndexer.exe causing problems after Search 4.0 update on Vista Home Premium system. - MSDN Forums and Desktop Search help has no recent advice.

I’ll try doing a windows update, then if that doesn’t work a uninstall/reinstall cycle.

Windows Search was much happier when I was using Office 2003. It hasn’t been the same since I went to 2007.

Update 10/20/08: I miss Lookout for Outlook. Also, Spotlight and all of OS X. Anyway, the Windows Update and reinstall didn't work. This time I'll uninstall, track down my index and trash it, and try again. As before the index is built, everything looks fine, but searches return nothing.

Update 10/20/08: Still not working. I'm running out of ideas. Next step is to uninstall Windows Search 4 and install Google Desktop Search! Instant search works in Outlook, but desktop search doesn't work at all. From a post on MSDN that I wrote:

A few days ago Windows Search 4 stopped working in my corporate XP desktop (all updated). All deskbar searches return "Nothing found in All locations for query ..." regardless of the query. I can't indentify any precipitating event but this is a managed corporate desktop. Anything can happen to it.

Web searches work. Instant searches in Outlook 2007, which use the Windows Search engine, are also working.

The index is fine and it's being maintained correctly.

I've run Office 2007 Diagnostics. I've rebuilt the index. I've uninstalled Windows Search and reinstalled. I've reviewed the Applications event log. I've deleted the index and indexed only a small bit of Outlook 2007. I've relocated my index to a new directory.

Nothing makes any difference. Instant Search works, the indexer works, Windows Search 4 doesn't work.

My corporate desktop is encrypted (SafeBoot), but I've not run into any problems there.

I don't know what to try next. Actually, my next step is to uninstall Windows Search 4 and install Google Desktop Search. I need search to work and I can't go on a lot longer without it.

Later I also reinstalled Office Pro 2007 -- to no effect. I did try Google Desktop Search, but for me it was far too simplistic. It also crashed every day.

Update 10/25/08: The hardest problem I've solved in years. I finally found a 2006 post on an MSDN board about the same problem. Search worked in Outlook 2007, but not from the desktop. It turns out that desktop search uses Microsoft's data query infrastructure (MDAC), and that infrastructure can be broken.

Repair of a broken MDAC stack is occult. Fortunately Paul Nystrom had the answer in 2006

http://forums.microsoft.com/msdn/ShowPost.aspx?PostID=901078&SiteID=1

This generally occurs when you have a corruption in your MDAC stack. You can find instructions for repairing your MDAC stack here (note this solution is not officially supported by Microsoft):

http://www.pqsystems.com/kb/activekb/questions/165/

For some additional information:

MDAC stands for Microsoft data access components. These components allow WDS to query it's index for resutls. When MDAC gets corrupted WDS can not retrieve results from the index resulting in empty query results.

Paul Nystrom - MSFT

I followed the repair advice on the referenced page (I have XP SP 3 installed):

How to repair a copy of MDAC 2.8 SP1 on Windows XP with SP2 installed.
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Right-click on C:\Windows\Inf\mdac.inf and choose "Install".

. ..point to the i386 folder in one of these places:

1. C:\Windows\ServicepackFiles\i386 (it may not like this location, if not, go to the next one)

2. The \i386 folder on your XP installation CDROM.

This reinstalls and repairs MDAC 2.8.

I used the servicepack files folder first. When asked for a file that wasn't in there I used the \i386 folder our corporate IT had on my drive.

It worked. Thank you Paul.

Hardest fix in years. Without Windows Live Search and Google I wouldn't have had a chance.

So what happened? My guess is that there's a problem with the sequence I took, moving through Windows Search 4 on Office 2003, then XP SP 3, then Office 2007. Somewhere in that sequence I broke MDAC.

The Wikipedia article on MDAC is informative:

The current version is 2.8 service pack 1, but the product has had many different versions and many of its components have been deprecated and replaced by newer Microsoft technologies. MDAC is now known as Windows DAC in Windows Vista.

XP is starting to remind me of Windows 98.