How to use Thai fonts with Word?

I have a new iMac with Lion and when I switch to Thai it works in Finder, Dreamweaver, Excel and Open office everywhere except Word. (New version of word for the Mac)

When I open a new Word document and select a Thai font (which I see in the list of fonts) it seems like it types in Thai for a split second and then changes to empty squares.

I am sure the answer is a simple one like check a unicode box or something like that but I am not sure.

Does anyone know what I should do?

I got it to work by selecting different fonts some seemed to work better than others.