After a catastrophic hard drive failure, I've reinstalled everything on a clean machine, and the aforementioned problem no longer seems to affect me. Just in case it's helpful, here's a new copy of my Visual Studio "About" dialog:
Microsoft Visual Studio 2010
Version 10.0.30319.1 RTMRel
Microsoft .NET Framework
Version 4.0.30319 RTMRel
Installed Version: Professional
Microsoft Office Developer Tools 01018-532-2002181-70269
Microsoft Office Developer Tools
Microsoft Visual Basic 2010 01018-532-2002181-70269
Microsoft Visual Basic 2010
Microsoft Visual C# 2010 01018-532-2002181-70269
Microsoft Visual C# 2010
Microsoft Visual C++ 2010 01018-532-2002181-70269
Microsoft Visual C++ 2010
Microsoft Visual F# 2010 01018-532-2002181-70269
Microsoft Visual F# 2010
Microsoft Visual Studio 2010 Team Explorer 01018-532-2002181-70269
Microsoft Visual Studio 2010 Team Explorer
Microsoft Visual Web Developer 2010 01018-532-2002181-70269
Microsoft Visual Web Developer 2010
Add Reference Dialog Plus! 1.0
An significantly enhanced Add Reference dialog for managed code projects.
Crystal Reports Templates for Microsoft Visual Studio 2010
Crystal Reports Templates for Microsoft Visual Studio 2010
Document Well 2010 Plus 1.0.10916.0
This package provides configurable behavior for the Document Well and its tabs. Please be sure to let us know what you like/dislike about this extension.
ExtensionUpdateCheck 1.0
Shows a notification icon in the system tray after Visual Studio startup if there are updates available for any installed extensions.
JetBrains ReSharper 5.1 C# Edition build 5.1.3000.12 on 2011-01-28T04:05:56
JetBrains ReSharper 5.1 package for Microsoft Visual Studio. For more information about ReSharper, visit http://www.jetbrains.com/resharper/. Copyright © 2003–2011 JetBrains, Inc.
Microsoft Visual Studio 2010 SharePoint Developer Tools 10.0.30319
Microsoft Visual Studio 2010 SharePoint Developer Tools
ViEmu (Symnum Systems S.L.U.) 2.5.14
ViEmu: Vi/vim emulation for Microsoft Visual Studio 2010. (c) 2005-2010 Symnum Systems S.L.U. Please visit http://www.viemu.com for details.
Visual Git
Henk Westhuis
It's mostly the same, and certainly has the same versions of ViEmu and Resharper. I guess I very probably configured things a little different or installed them in a different order this time.