Ok I've fixed it so just in case anyone else has something similar ....
There must be some difference between the two jdks with picking up system envs because when I started glassfish with 1.5 I could see it was using a hostname which *wasn't* in my /etc/hosts/ file. So, I added this same name as an alias in there and now it works. (ie I'm gussing soylatte looks in there but sun jdk doesn't)
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