I was intrigued by the following Outlook 2010 error message which I had not seen before:

Instant Search is not available when Outlook is running with administrator permissions. However, it was not. A Microsoft support note suggested another possible reason: Windows Search not running. However, it was running. It was clear though that Outlook searches were not being indexed, making them unusable on my low-powered netbook.

Eventually I figured it out. I’d just run an update for the excellent Battery Bar, which installs an batter monitor in the Windows 7 taskbar. In order to shut down the running instance, the Battery Bar setup restarted Explorer. Since the installer was running with elevated rights, Explorer had presumably restarted with elevated rights, and this somehow triggered the error in Outlook.

I recall that it it is tricky (but possible) for an elevated process to start a non-elevated process, so I guess Osiris needs to tweak its setup application.

The solution from my point of view was to restart Windows.