My application does not use a ReportViewer, but rather generates a pdf file and sends it to the client as a download, using the following code:
ReportDocument repDoc = new ReportDocument();
// update the crystal report database connection
// send the resulting document to the user (as PDF).
repDoc.ExportToHttpResponse(formatType, Response, true, "Report");
At first, I fixed this problem quite easily, by altering one value in the registry: