Apply trace on RAS and look for errors in the RAS logs at the same timestamp.
These errors come for various errors and tracing RAS would give us a better idea.
It might hapen that you observe these errors for reports which takes more than the RAS timeout to export the reports.
Post getting the RAS logs you can try below steps if we see timeout errors in RAS logs.
Copy clientSDKOptions.xml file from <BO install path>\SAP BusinessObjects\SAP BusinessObjects Enterprise XI 4.0\java\lib to the machine where your app is running Open clientSDKOptions.xml and change CORBARequestTimeOut from 600000 to a value large enough to allow the report to render, for instance 1200000. Default value is 600000 (10 minutes)
Specify the location of the clientSDKOptions.xml file at run-time. In your JSP or Java files, use the Java method setProperty from the System class. Set the system property indicated by the ras.config key to the specified directory as: system.setProperty("ras.config","c:\temp"). This function call specifies that the clientSDKOptions.xml file in c:\temp is to be used for locating RAS servers.
Thanks,
Prithvi