font problems with WordXP

We are currently using Windows 2000 with WordXP and have installed cg times font for use with our documents. We have had problems with the cg times font files arbitrarily coming up empty. We have had the same problems with the symbol font file. When this happens Word replaces the font with Courier, which changes pagination, etc. Has anyone else encountered font files coming up empty? The file doesn’t go away but its contents disappear.