Problems opening reports (JRC engine)

I've an website (asp.net) that contains multiple reports, and sometimes i'm getting this error:

System.Runtime.InteropServices.COMException (0x80041811): Operação não permitida. A document processed by the JRC engine cannot be opened in the C++ stack at CrystalDecisions.ReportAppServer.ClientDoc.ReportClientDocumentClass.Open(Object& DocumentPath, Int32 Options) at CrystalDecisions.ReportAppServer.ReportClientDocumentWrapper.Open(Object& DocumentPath, Int32 Options) at CrystalDecisions.ReportAppServer.ReportClientDocumentWrapper.EnsureDocumentIsOpened()

When this hapens i've to recycle the application pool and after the report starts working again.

I've the latest version of SAP runtime.

Can anyone help me?

Thanks