bug with JDK 1.6.0.29?

I came across an weird issue, We communicate with an existing web service from one of our new projects, when I try to execute the project from my system which talks to the web service in test server (GlassFish), The request was failing in server end with the following error.

"The markup in the document preceding the root element must be well-formed."

And the error was intermittent. The same project executes fine in my all other teammates systems. After doing all the normal initial trouble shooting (syncing with the latest in code base, clean up the maven repo, capturing outgoing message and try from SoapUI etc). The only difference between my system and others were jdk version, I was using 1.6.0.29, and other were using 1.6.0.27. After I reduced my JDK version to 1.6.0.27, it started to work fine. So Weird, I did not find any difference in the outgoing SOAP message too. I will update this post if I found any thing useful in this.