Problems when launching soapui multiple test in Junit

Hi everyone, I'm having a problem when I'm launching more than one soapui test in Junit (the first one passes but the other end in an OutofMemory error.

I'm doing the thing like that :

 @Before
   public void setUp()
   {
      runner.setProjectFile(test.xml");
      runner.setOutputFolder("./target");
   }

I've also a teardown method which set runner to null.

So this one is called each time I'm running one of these test :

   @Test
   public void test0401() throws Exception
   {
      runner.setTestSuite("M04");
      runner.setTestCase("M0401");
      runner.run();
   }
   
   @Test
   public void testSquelette() throws Exception
   {
      runner.setTestSuite("M04");
      runner.setTestCase("M0416");
      runner.run();
   }

Ath the execution of the second test I get the following logs :
11:12:33,875 WARN [SoapUI] Missing folder [D:\workspace\test-auto-simu\.\ext] for external libraries
11:12:33,875 INFO [DefaultSoapUICore] initialized soapui-settings from [d:\Documents and Settings\admin\soapui-settings.xml]

this line should continue with 11:12:04,562 INFO [WsdlProject] Loaded project from [test.xml] just like the first one, but it's not and is ending with a java.lang.OutOfMemoryError: Java heap space

Do someone have an idea on the problem ?