Generate PDF output

Hello,
I have a problem with FastReport printing (VCL).
During the generation, error occurs randomly. Reports are generated repeatedly, each time with different data (using the Filter property).

Below is a procedure for generating a report.


Generate a report:::::::::::::::::::::::::::::::::::: (for each type of document I create one instance, then I change only the filter)

TfrxReport* report = new TfrxReport(query);
report->EngineOptions->MaxMemSize = 1024;
report->EngineOptions->UseFileCache = true;
report->EngineOptions->EnableThreadSafe = true;
report->EngineOptions->SilentMode = true;

report->LoadFromFile(.....);
//----sets variables
report->Variables->DeleteVariable(...);
report->Variables->AddVariable(..., ..., ...);
.....
//::::::::::::::::::::::::::::::::::::::::::::::::::

After determining the type of report and obtaining its instance I change the filter:::::::::

TfrxADOQuery * query = findReportQuery(report); // method finds the first TfrxADOQuery Components[...] member of the 'report' instance
query->Filter = ...
query->Filtered = true;
//::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

Finally report gets prepared for printing::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

report->PrepareReport(true); -- // this method ocassionally throws exceptions like "Dataset 'ADOQuery1' does not exist" or "out of memory"
report->Print();

---- exception is thrown randomly (the same set of reports gets sometimes printed successfully, sometimes not. With completely the same data and settings.)

Thanks for help in advance.