http://bugs.winehq.org/show_bug.cgi?id=28486
--- Comment #16 from Hans Leidekker hans@meelstraat.net 2012-04-29 06:53:34 CDT --- (In reply to comment #15)
.NET 2.0 is not a prerequisite for Office 2010 Professional Plus. The installer succeeds on Windows XP without it and without a machine.config file, and it does not install them itself, either. That makes it a Wine bug.
Likely because of the registry keys that indicate that .NET is installed. This should also be fixed by the wine-mono package, which will remove those keys if you uninstall it.