je ne trouve une référence du problème que sous la msdn :
http://msdn.microsoft.com/workshop [...] s/font.asp
"As of Internet Explorer 6, when you use the !DOCTYPE declaration to specify standards-compliant mode, the following conditions apply to this property.
The font-size and font-family values must be declared. If font-size and font-family are not declared, or are not in the correct order, the font property is ignored.
All specified values must appear in the correct order. Otherwise, the font property is ignored."