javax.comm.properties is a properties file that is needed by the Java Communications 2.0 API. It's one of those mysterious files where nobody really knows where to put it to get stuff working. Current directory? Some subdirectory of your JDK? Some subdirectory of your JDK? Who knows... gotta try them all.
Anyway, I have found a workaround where you don't need the file. Add the following lins of code and there's no more need for the pesky little properties file.
String driverName = "com.sun.comm.Win32Driver";
commDriver = (CommDriver)Class.forName( driverName ).newInstance();
BTW, Java Communications 3.0 API is not supported on Windows. Duh?!? Hello?!? Who came up with that great idea?