Do you have pl/sql code written in that report? or you are passing parameters in deocde mode?
Well this abnormal conditions appers when Ora reps are not able to understand the correct return value...! I guess this might be the case...check your coding!
this is due to the path of the printer
1) map the network printer and set it as default
2) in ur code give the exact path of the printer from u r terminal in the parameters that u have to give at the print command