The solution? The only one I've found is to re-format and install on a file system that is not case sensitive. After hearing back from HP's tech support, they confirmed the problem and the solution:
Thank you for contacting HP Total Care.I only wish they had mentioned that anywhere in the online troubleshooting section. Sigh.
The software for the Photosmart C6180 is not supported on a case sensitive partition. You will have to install the drivers on a case-insensitive partition.

