Today I have discovered the solution to a problem that began yesterday.
Some of our client computers running Office Outlook 2007 (connecting to Exchange 2007) started crashing, when performing a search on any folder.
The error would crash Outlook and ask the user if they wish to restart. The error is reporting the problem in EMSMDB32.DLL.
After reviewing the event logs I discovered that the error began occuring after Windows Update installed the NEW version of KB2412171 (This originally caused a problem when released in December of last year and the new version also has this bug).
Uninstalling update KB2412171 from the affected machines resolved the problems immediately.
Hopefully this information will assist some of you in your troubleshooting.