http://bugs.winehq.org/show_bug.cgi?id=24201
--- Comment #1 from Vincent Povirk madewokherd@gmail.com 2010-08-29 13:10:47 CDT --- A google search gave me the MSDN documentation: http://msdn.microsoft.com/en-us/library/ms680683%28VS.85%29.aspx
Apparently, the "caller" may be from a different apartment, I guess implying that the call has been marshalled.