Try saving the report in Excel format from Webi Rich Client, IF there is any report desin issue it will fail in Webi Rich Client.
For BILaunchap:-
increase "Maximum Character Stream Size" in Webi Processing Server and restart WPS in CMC.
check the behaviour in Applet as well as HTML
Also if you are using any Load Balancer or SSL then it will cause issue.
Check behaviour with the direct tomcat URL.
there are issue with Image as well if you have any try removing and exporting again
Also check SAP note 1900005 1911303