SOAPUI max running services amount limit

Noticed, that SOAPUI can run max 5 services at a time (running them using configuration file).

For example, if I have 7 services, the last two gives an error:

13:34:49,368 ERROR [SoapUI] An error occurred [Address already in use: bind], see error log for details
java.net.BindException: Address already in use: bind
        at sun.nio.ch.Net.bind0(Native Method)
        at sun.nio.ch.Net.bind(Unknown Source)
        at sun.nio.ch.Net.bind(Unknown Source)
        at sun.nio.ch.ServerSocketChannelImpl.bind(Unknown Source)
        at sun.nio.ch.ServerSocketAdaptor.bind(Unknown Source)
        at org.mortbay.jetty.nio.SelectChannelConnector.open(SelectChannelConnector.java:216)
        at org.mortbay.jetty.nio.SelectChannelConnector.doStart(SelectChannelConnector.java:315)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
        at org.mortbay.jetty.Server.doStart(Server.java:235)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
        at com.eviware.soapui.monitor.JettyMockEngine.startMockService(JettyMockEngine.java:147)
        at com.eviware.soapui.impl.wsdl.mock.WsdlMockRunner.start(WsdlMockRunner.java:201)
        at com.eviware.soapui.impl.wsdl.mock.WsdlMockRunner.<init>(WsdlMockRunner.java:71)
        at com.eviware.soapui.impl.support.AbstractMockService.start(AbstractMockService.java:250)
        at com.eviware.soapui.impl.support.AbstractMockService.start(AbstractMockService.java:223)
        at com.eviware.soapui.impl.support.AbstractMockService.start(AbstractMockService.java:59)
        at com.eviware.soapui.tools.SoapUIMockServiceRunner.runMockService(SoapUIMockServiceRunner.java:197)
        at com.eviware.soapui.tools.SoapUIMockServiceRunner.runRunner(SoapUIMockServiceRunner.java:124)
        at com.eviware.soapui.tools.AbstractSoapUIRunner.run(AbstractSoapUIRunner.java:202)
        at com.eviware.soapui.tools.AbstractSoapUIRunner.run(AbstractSoapUIRunner.java:137)
        at com.eviware.soapui.tools.AbstractSoapUIRunner.runFromCommandLine(AbstractSoapUIRunner.java:112)
        at com.eviware.soapui.tools.SoapUIMockServiceRunner.main(SoapUIMockServiceRunner.java:66)

Any ideas where this limit came from? Is it some Windows propery in register or SOAPUI itself limits these?

On other machine, there are no limits, and all services are running well.