Hi,
It seems your BI4.0 Launchpad has session timeout as "at com.sap.webi.ui.Helper.isSessionTimeOut(Helper.java:429)."
I'd suggest you to increase your BI4.0 session timeout. See "Increase timeout in BusinessObjects 4.0?" on http://scn.sap.com/thread/3351650
Hope this helps,
Jin-Chong