1. Click Start, click Control Panel, and then double-click Regional and Language Options.
2. On the Languages tab, select the Install files for complex script and right-to-left languages (including Thai) check box.
3.Click on Details.
4.On the Advanced tab, select the Extend support of advanced text services to all programs check box.
5.Click OK to dismiss the Text Services and Input Languages window.
6.Click OK to dismiss the Regional and Language Options window.
I dont have any fonts other than English installed, so cant post screenshots. It was for XP, so you have to digg somewhat more.