I would pay attention to that warning and get the printer and the application into conformity.
Now, where you see the magenta cast in the prints, do you know for sure that it isn't in the image file as well, and you are not seeing it because of a display calibration/profiling issue? Use the eyedropper in Photoshop, with the Info panel set to Lab, to see whether when you pass the eyedropper over the areas where the print looks magenta you are getting a* values greater than 0. If so, it would indicate a Magenta presence that the printer is reproducing but the display is not showing to the naked eye. Also try printing the file using Printer Manages Color instead of an ICC profile, to see whether the Magenta cast persists. If not, the problem could be profile quality.