if your report using Stored Procedure (SP) where there are some parameters (or only one param) in the SP then it will prompt you whenever you run the report even you didn't put any param inside CR.
other word: param(s) from SP will automatically included in CR.
but if there is no param(s) in your SP then you can consider what lockwelle suggest.
in this case, please check any variables that using a 'reserve words'.
hope it help.