Perplexing OTF Font Problem Locking up InDesign


We've been developing an OTF font in Fontlab Studio 5.0.2., Windows, periodically generating the font and using it in InDesign CS3, Windows for testing. Everything has been going well until yesterday when InDesign started locking up while trying to output a PDF with the font. InDesign also cannot display the font in its glyph pallet. Again, it locks up.

I have Roman, Italic, Bold and BoldItalic fonts. Roman and Italic have the problem, Bold and BoldItalic do NOT! Compared to other professional fonts there is little by way of features and classes and I've tried deleting all the classes and features and copying them from one of the fonts that works.