I use the 7740 connected with ethernet. Printing via 2 PCs and from an iPad worked fine till 3 hours ago. Suddenly it's not possible to print in color from one PC, it just prints in grayscales. It still works from the other PC and the iPad so.
I tried re-installing the driver first by removing and re-installing the HP-Software manually, then by using the HP PrintDoctor (5.3.1) - but stillprinting is black&white only
Strange thing: On the PC where everything works the printer-setting are labled "HP OfficeJet Pro 7740 series PCL-3" (with Resolution 1200 DPI) while on the PC where it doesn't work it's just ""HP OfficeJet Pro 7740 series" (with Resolution 600 DPI) although I donwloaded the latest driver directly from the HP-Homepage.
The print-settings differ as well: While I can choose "print in Grayscale" on the PC where everything works, the field (and some others) are missing on the other PC.
Any idea what I could do except from re-installing the software the 12th time?