http://bugs.winehq.org/show_bug.cgi?id=20311
--- Comment #32 from Nikolay Sivov bunglehead@gmail.com 2010-10-21 15:31:03 CDT --- Wylda, this is most likely fixed by 657f64dd064cab9ee4b17867052aee61f668bd46. Please try again with today git version (wine-1.3.5-168-gd4e8f30).
At least saving to IStream with proper encoding should work fine.