tests which worked in v 4.0.0 fails in v 4.5.0

Hello All,

I have a very simple test , which just sends a REST request and checks for few simple assertions in the response.
This worked perfectly fine in soapUI version 4.0.0

But I had to upgrade to version 4.5.0.
But since then , the same tests which previously worked fine, are all failing . giving the following errors

ERROR LOG:
=============

ERROR:java.lang.ClassCastException: org.apache.http.message.BasicHttpRequest cannot be cast to org.apache.http.impl.client.RequestWrapper
java.lang.ClassCastException: org.apache.http.message.BasicHttpRequest cannot be cast to org.apache.http.impl.client.RequestWrapper
at com.eviware.soapui.impl.wsdl.support.http.HttpClientSupport$SoapUIHttpRequestExecutor.preProcess(HttpClientSupport.java:93)
at org.apache.http.impl.client.DefaultRequestDirector.createTunnelToTarget(DefaultRequestDirector.java:830)
at org.apache.http.impl.client.DefaultRequestDirector.establishRoute(DefaultRequestDirector.java:739)
at org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:565)
at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:415)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:820)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:754)
at com.eviware.soapui.impl.wsdl.support.http.HttpClientSupport$Helper.execute(HttpClientSupport.java:218)
at com.eviware.soapui.impl.wsdl.support.http.HttpClientSupport.execute(HttpClientSupport.java:329)
at com.eviware.soapui.impl.wsdl.submit.transports.http.HttpClientRequestTransport.sendRequest(HttpClientRequestTransport.java:251)
at com.eviware.soapui.impl.wsdl.WsdlSubmit.run(WsdlSubmit.java:123)
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
at java.util.concurrent.FutureTask$Sync.innerRun(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)

I am running soapUI on a Windows 7, 32 Bit machine.
Could anyone please help with this problem ?
Regards
Vikas