I recently upgraded to Windows 7 RTM. When I hit the Windows key, no search results were being returned. Only standard items from control panel etc. The Windows search service appeared not to be running. When I tried to start the service from services.msc, I got an error:
Windows could not start the Windows Search service on Local Computer.
Error 1224: The requested operation cannot be performed on a file with a user-mapped section open.
Since those things always happen when you're urgently working on something else, I decided to just uninstall and reinstall Windows Search from "Turn Windows Features on or off". After a reboot, I was surprised to find that hitting the Windows key resulted in the start menu opening without the search box. It is also fascinating how reliant one becomes on just typing a couple of initial characters and getting a list of suggestions from search. Now I had to reinstall and figure out where that was again. (I normally type Windows Key, then "features" to select Programs And Features. Now I had to navigate the control panel.
After reinstalling Windows Search, still (somewhat luckily) the same error. OK. Grumpf. All other projects put aside. ProcMon.
Starting Process Monitor and then trying to restart Windows Search. When the error above pops up, I stopped Procmon. Now filter in ProcMon only on SearchIndexer.exe (the executable name of the Search service). Most of the files that are used by the service either return "SUCCESS" or "FILE LOCKED WITH ONLY READERS". But then I found this result "USER MAPPED FILE". That looked somewhat in line with the error. The path of the file was
C:\ProgramData\Microsoft\Search\Data\Applications\Windows\Projects\SystemIndex\Indexer\CiFiles\0001000C.wid. When I tried to use Windows Explorer (first enable viewing Hidden and System files) I had some interesting flickering issues. Folder contents would show up in the right-hand pane, only to disappear with a fraction of a second. One can only investigate so much at a time though. Moving on.
With an elevated command prompt I was able to get to the file. I moved the file to my desktop. Restarting the service and Eureka. In the event log a whole bunch of errors and warning were logged. Windows Search complained about the index being corrupt (most likely because the offending file was missing).
But search is back and running again.