[Res] Error While Running Rest Test Cases

I am getting below error for While running Rest Test Cases...Anyone have idea what is this?
XML tab[/size]
<Fault xmlns="xyz">
<errorMessage>Could not read JSON: Illegal character ((CTRL-CHAR, code 31)): only regular white space (\r, \n, \t) is allowed between tokens
at [Source: com.elsevier.webservices.ae.security.filter.CustomRequestWrapper$ServletInputStreamWrapper@66c8dc96; line: 1, column: 2]; nested exception is com.fasterxml.jackson.core.JsonParseException: Illegal character ((CTRL-CHAR, code 31)): only regular white space (\r, \n, \t) is allowed between tokens
at [Source: com.elsevier.webservices.ae.security.filter.CustomRequestWrapper$ServletInputStreamWrapper@66c8dc96; line: 1, column: 2]</errorMessage>
<errorType>SYSTEM</errorType>
</Fault>

Error Log
Wed Apr 30 10:28:19 EDT 2014:ERROR:java.lang.OutOfMemoryError: unable to create new native thread
java.lang.OutOfMemoryError: unable to create new native thread
at java.lang.Thread.start0(Native Method)
at java.lang.Thread.start(Unknown Source)
at com.eviware.soapui.impl.rest.panels.request.inspectors.schema.InferredSchemaInspector.afterSubmit(InferredSchemaInspector.java:156)
at com.eviware.soapui.impl.wsdl.WsdlSubmit.run(WsdlSubmit.java:157)
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)