I believe I have correlated the error I get every time I exit CoreGen with java; i.e., I think it is the java program that is causing the error as it attempts to close. The error I get relates to attempted access of low memory (I don't recall the address right now--I'm at home--but I believe it is consistent.) I got this under ISE Alliance 5.x whenever I ran CoreGen; now that I've upgraded to 6.x, I also get it when I start up. Other than the irritating message, things seem to work properly.
I briefly checked support on Xilinx's web site; didn't see anything relevant using "java" as the key word.
Jason