Data Exception running more than one report at a time on the server

InfoTwo

We are using ReportEngine 4.4.0 on tomcat to display reports using Pojo data sources.<br>
When running just one report it displays fine. If one report is run and another is started while it is running the second one displays fine but the first one has a data exception and says there is an error in the report document and that the archive file has been closed. If you refresh the screen it loads fine when it is the only report running.<br><br>
We are using the birt:viewer tag. We don't use the reportDocument attribute. We tried using the reportDocument attribute and set it to a value of dateTime.rptdocument where dateTime is the time stamp to give it a unique file name. This did not work. Got the same error.<br><br>
Is this some sort of timeout issue and if so how might that be fixed?