Since a few days my 4-year old L7780 (Product Number: C8192A, Serial Number: {Personal Information Removed}) continuously crashes. The display shows a red and blue screen, overlaid by a white on black message "Turn power off then on again". Pressing the power button results in an error messages that indicates an "Improper Shutdown".
Repeating the power-on procedure a couple of times (sometimes the following self-test enables the printer again, sometimes it doesn't and immediately crashes again) eventually re-enables the printer - yet only for about 5-10 minutes before it crashes again. During the period when it is online it works perfectly fine.
Print Doctor v4.0 doesn't find any error. The printer and Solution Center complain about an expired (but full) ink cartridge.
Any idea what's going on?