cfchart does not generate HTTP headers. When no headers are provided, IIS 6 examines the data and presumes headers are included in the data (for legacy ISAPI extensions). If the image data accidentally contains a binary value that looks like a line-end near the beginning of the data, IIS 6 misinterprets the beginning of the image data as an HTTP header.
Macromedia has created an individual hot fix for this problem that explicitly generates HTTP headers before the chart data.
Both ColdFusion MX 7 cumulative and individual hot fixes are installed in the ColdFusion MX Administrator. The installation process is the same for all platforms and installation choices.
The ColdFusion MX 7 hot fix JAR file does not need to be retained after installing it with the ColdFusion Administrator. The file has been copied into the correct location.
The ColdFusion MX 7 hot fix JAR file will appear as a new entry in the System Information list.