This issue can be reproduced in comp-suite application:
1. Load the comp-suite application and navigate to Data Exporter -> Specify Columns page:
http://localhost:8080/comp-suite/showcase.jsf?grp=aceMenu&exp=dataExporterColumns
2. Check all the check boxes to exclude all columns of the data table.
3. Select Export File Type as 'PDF', and click on Export File button.
4. A Server Internal Error message occurs, and an error is thrown in the server log:

Nov 4, 2011 12:51:23 PM com.sun.faces.lifecycle.ApplyRequestValuesPhase execute
WARNING: The number of columns in PdfPTable constructor must be greater than zero.
java.lang.IllegalArgumentException: The number of columns in PdfPTable constructor must be greater than zero.
at com.lowagie.text.pdf.PdfPTable.<init>(Unknown Source)
at org.icefaces.ace.component.dataexporter.PDFExporter.exportPDFTable(PDFExporter.java:108)
at org.icefaces.ace.component.dataexporter.PDFExporter.export(PDFExporter.java:77)
at org.icefaces.ace.component.dataexporter.DataExporter.broadcast(DataExporter.java:48)
at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:759)
at javax.faces.component.UIViewRoot.processDecodes(UIViewRoot.java:935)
at com.sun.faces.lifecycle.ApplyRequestValuesPhase.execute(ApplyRequestValuesPhase.java:78)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:593)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:243)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:201)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:163)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:108)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:556)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:402)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:249)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:267)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:245)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:260)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)