Assertion failed: p != NULL, file ../../../src/share/native/sun/awt/font/t2k/t1.c, line 1974

I use a spring bean to create the DefaultManageableImageCaptchaService instead of a class (I'm not sure it's useful for my request)
<bean id="captchaService" class="com.octo.captcha.service.image.DefaultManageableImageCaptchaService"></bean>
to create the DefaultManageableImageCaptchaService singleton.

I'm using commons-collections-3.2.

Everything is fine under windows xp, but on the solaris one, I got this error.

Error while starting Tomcat
Assertion failed: p != NULL, file ../../../src/share/native/sun/awt/font/t2k/t1.c, line 1974
And Tomcat doesn't load completely.

I don't know if it is a system environment error (I've find that kind of stuff : http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5070518 which isn't very explicit) but the jCaptcha lib seems to be the one using fonts.

How to check usable fonts ?

Thanks