We have a trouble with Russian characters representation if .chm file is opened on the computer where English-language operating system is installed. Content frame is good but topic text is displayed using French and other diacritic characters. There is workaround, if you open IE and select in the main menu the VIew->Encoding->Autoselect item, then characters are displayed correctly.
When we used HTML Help workshop there was no such trouble. Do you know if it is possible to configure Flare project to open .chm file as it was when HTML Help workshop was used?