Firstly, I recommend you remove the program from your computer using its uninstaller or Add or Remove Programs feature (Control Panel > Uninstall a program) and reboot your computer. Next, go to Start > Control Panel > Appearance > Font > Font settings and press the Restore default font settings button. After that, try to install the fonts again. If you still have problems, try installing the Myanmar fonts provided by MyOrdbok. Also, if you want to type in Myanmar using your keyboard, download and install a Myanmar keyboard from Software Informer database.
