Bug: Problem with Merge Index whether user requested or automatic

Typical log entry is:
Error Program Unhandled exception: System.ArgumentOutOfRangeException: document id 2527 is outside valid range of [1, 2527)

Software version: 4.0a.
Reported by Dave Hooton.
Forum link: http://community.logos.com/forums/t/9650.aspx
See also http://community.logos.com/forums/t/9844.aspx

Status: confirmed