createReport method signature becomes invalid

I am using the createReport method on the JUnitReportEngine object. Most of the time, everything works fine. Occasionally I get a MissingMethodException that looks like the following:

groovy.lang.MissingMethodException: No signature of method: com.eviware.soapui.reporting.engine.junit.JUnitReportEngine.createReport() is applicable for argument types: (java.lang.String, com.eviware.soapui.eventhandlers.impl.EventHandlersTestSuiteRunListener, com.eviware.soapui.impl.wsdl.WsdlTestSuitePro, java.lang.String) values: [C:\Temp, com.eviware.soapui.eventhandlers.impl.EventHandlersTestSuiteRunListener@100db9d, com.eviware.soapui.impl.wsdl.WsdlTestSuitePro@11a6737, Single Page (Print)]
Possible solutions: createReport(java.lang.String, com.eviware.soapui.report.JUnitReportCollector, com.eviware.soapui.model.ModelItem, java.lang.String)
 at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.unwrap(ScriptBytecodeAdapter.java:55)
 at org.codehaus.groovy.runtime.callsite.PojoMetaClassSite.call(PojoMetaClassSite.java:46)
 at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:42)
 at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:108)
 at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:128)
 at Script1.run(Script1.groovy:10)
 at com.eviware.soapui.support.scripting.groovy.SoapUIGroovyScriptEngine.run(SoapUIGroovyScriptEngine.java:96)
 at com.eviware.soapui.support.scripting.groovy.SoapUIProGroovyScriptEngineFactory$SoapUIProGroovyScriptEngine.run(SourceFile:89)
 at com.eviware.soapui.impl.wsdl.WsdlTestSuite.runTearDownScript(WsdlTestSuite.java:528)
 at com.eviware.soapui.impl.wsdl.testcase.WsdlTestSuiteRunner.internalFinally(WsdlTestSuiteRunner.java:184)
 at com.eviware.soapui.impl.wsdl.testcase.WsdlTestSuiteRunner.internalFinally(WsdlTestSuiteRunner.java:42)
 at com.eviware.soapui.impl.wsdl.support.AbstractTestRunner.run(AbstractTestRunner.java:163)
 at com.eviware.soapui.impl.wsdl.support.AbstractTestRunner.start(AbstractTestRunner.java:77)
 at com.eviware.soapui.impl.wsdl.WsdlTestSuite.run(WsdlTestSuite.java:727)
 at com.eviware.soapui.tools.SoapUITestCaseRunner.runSuite(SoapUITestCaseRunner.java:571)
 at com.eviware.soapui.SoapUIProTestCaseRunner.runSuite(SourceFile:216)
 at com.eviware.soapui.tools.SoapUITestCaseRunner.runRunner(SoapUITestCaseRunner.java:403)
 at com.eviware.soapui.tools.AbstractSoapUIRunner.run(AbstractSoapUIRunner.java:158)
 at com.eviware.soapui.tools.AbstractSoapUIRunner.runFromCommandLine(AbstractSoapUIRunner.java:89)
 at com.eviware.soapui.SoapUIProTestCaseRunner

The code is the EXACT same between runs. I consistantly get this error when I run using the "Launch TestRunner" wizard. When I get this error via running the suite from the TestSuite editor (which is intermitent), I have to restart my computer and it starts working again (restarting soapUI doesn't help). I am using version 4.5.2. Here is the code I am using:. Here is the code I am using:

engine = new JUnitReportEngine()
listeners = testSuite.getTestSuiteRunListeners()
fileResult = engine.createReport("C:\\Temp", listeners[0], runner.testSuite, engine.SINGLE_PAGE_PRINT_REPORT_FORMAT)
String fileContents = new File("C:\\Temp\\index.html").text
message = fileContents