What is error 0xc05d1281

Apparently its a Ink System Failure. Here's an email thread for comment for HP C6180 with error 0xc05d1281 => http://www.fixyourownprinter.com/forums/printer/50063

It's posted somewhere in the middle of the thread.

Here's a solution to reset your printer to factory defaults without using your ink for recalibration.

1. Unplug the printer and wait 30 seconds for power to discharge.
2. Plug in the printer.
3. Hold the CANCEL and OK buttons simultaneously, and keep them depressed while you hit the ON button. This resets the printer.
4. When the printer turns on, if you still get the error message, it's OK. Then perform the steps listed above, starting with pressing the * and # key.
5. After you perform the steps listed above, when you are at the step at the end where you are pressing the cancel button until you get to the WELCOME screen, if at some point you see a message, “Inproper shutdown, hit OK”, go ahead and hit OK and the Welcome screen should appear.
One thing that is nice about this method is that it doesn't use up all your ink doing a recalibration.