SoapUI progress indicator modal window freezes

My SoapUI 4.5.1 running on Linux Enterprise 6 freezes midway during execution of load tests, or SOAP & REST test steps.

SoapUI : soapUI 4.5.1, Build [internal], Build Date 2012/06/27 13:56
OS: Linux 2.6.32-279.14.1.el6.x86_64 #1 SMP Mon Oct 15 13:44:51 EDT 2012 x86_64 x86_64 x86_64 GNU/Linux

I have included a screen shot of SoapUI when it freezes.


I have Xms1024m and Xmx3072m.
I have "checked" - "Discard OK results" in Test case Options.

Is this a common problem with SoapUI? Is there a way I can make this go away, or do I have to upgrade to SoapUI Pro.

Thanks for the Great Software.

Regards,
Vivek