FIX - I'm using the ASP.NET 3.5 Charting Controls in SharePoint 2010 to render charts - but the charts don't print out in Internet Explorer (they're fine in Firefox). Why?

Internet Explorer seems to have to re-download the images generated by the charting control when printing them - if the Chart Image Handler (ChartImg.axd) setting is at deleteAfterServicing=true, then the subsequent request to render the chart with that same GUID (for printing) will fail.

To resolve, you can change the setting on your web.config for "deleteAfterServicing" to false so it doesn't automatically remove the requested image each run.

<add key="ChartImageHandler" value="storage=file;timeout=20;dir=c:\inetpub\YourApplicationName\temp\;deleteAfterServicing=false">

It is also best to have a cleanup job on this directory depending on your space requirements and number of chart requests made to your site.

DDK