The JBuilder support FAQ has the following fix:

The font that the JVM is looking for is "symbol.ttf". This font should be available on any Windows machine. You need to get a copy of the font and copy it to the JDK fonts directory, for example "/usr/local/jdk1.2.2/jre/lib/fonts".

In the "fonts" directory there is a file named "fonts.dir" that lists the available, scalable fonts for the Sun JDK. Edit this file (you may need to be root) to include the symbol.ttf font file like:

symbol.ttf -urw-symbol-medium-r-normal--0-0-0-0-p-0-adobe-fontspecific

You may notice whitespace in the file after the other font names. Note that these are spaces and not tabs. After you have added the above line, increment the number on the first line of the file by one (to indicate the total number of fonts listed in the file).