Report Error-Report can not be opened ;report an incident

I am executing one custom report in C4T and it is throwing the error Report Error-Report can not be opened ;report an incident. We have tried to extract the data in small chunks but still the problem continues.The report is built on join data source which combines of 5 joined data sources ,previously the report was working fine but now in the data source one row with the same characteristic field is getting generated twice even if we delete the duplicated row the row appears after saving.

Can anybody help me in solving this issue?