FSG Reports not generating any output when running with 'Content Set/Segment Override'

Hello Friends,

FSG reports are not generating any output when running with 'Content Set' Or 'Segment Override' options. This has started happening from today morning Only. We have around 50+ Operating Units and the users were able to get the output till last Friday i.e 31-AUG-2012 with the same parameters. This Obviously indicates something must have happened in last 3 Or 4 Days, but we certainly don't know what was that?? 

On the other hand, same FSG reports are generating the outputs in UAT/DEV instances which were cloned from Production last month. We have done all the basic investigation, whatever we could, but couldn't find out what the exactly issue is. I then raised an SR with Oracle Support, who are kept on asking generic info rather than focusing on our issue. It has become very critical as none of the users able to get the outputs from report.