Looks like the PSOSubpopulation.java file may not have been committed  
to CVS post minGene/maxGene updates.

Here's a patch to fix it (I think):

Index: PSOSubpopulation.java
===================================================================
RCS file: /cvs/ecj/ecj/ec/pso/PSOSubpopulation.java,v
retrieving revision 1.2
diff -c -r1.2 PSOSubpopulation.java
*** PSOSubpopulation.java	29 Oct 2007 23:35:44 -0000	1.2
--- PSOSubpopulation.java	11 Feb 2008 00:39:01 -0000
***************
*** 109,115 ****
           if (loadInds == null)  // we're generating new individuals,  
not reading them from a file
               {
               FloatVectorSpecies fvSpecies =  
(FloatVectorSpecies)species;
-             double range = fvSpecies.maxGene - fvSpecies.minGene;

               for (int i = 0; i < individuals.length; i++)
                   {
--- 109,114 ----
***************
*** 119,124 ****
--- 118,124 ----
                   for(int j = 0; j < prevInd.genomeLength(); j++)
                       {
                       double val = prevInd.genome[j];
+                     double range = fvSpecies.maxGene(j) -  
fvSpecies.minGene(j);
                       do
                           prevInd.genome[j] = val + (range *  
initialVelocityScale) * (state.random[thread].nextDouble()*2.0 - 1.0);
                       while (prevInd.genome[j] < fvSpecies.minGene(j)  
|| prevInd.genome[j] > fvSpecies.maxGene(j));