Maybe error indexing an Outlook item?

net stop wsearch (might have to set service to "Disabled")

Regedit -> HKLM\Software\Microsoft\Windows Search

Give self Full Control -> "SetupCompletedSuccessfully" change to "0"

For each of following keys, give self Full Control and Take Ownership (& propogate), then delete

HKLM\Software\Microsoft\Windows Search\Applications\windows
HKLM\Software\Microsoft\Windows Search\CatalogNames\windows
HKLM\Software\Microsoft\Windows Search\Databases\windows
HKLM\Software\Microsoft\Windows Search\Gather\windows
HKLM\Software\Microsoft\Windows Search\Gathering Manager\Applications\windows
HKLM\Software\Microsoft\Windows Search\UsnNotifier\windows

rd %ProgramData%\Microsoft\Search\Data\Applications\Windows /S /Q

Set Windows Search to "Automatic"

net start wsearch

Check "SetupCompletedSuccessfully" now has value "1"