I have had this C309a for several years now and, unless someone here can give me an answer, am ready to ditch it and HP. I have this printer networked with a four computer network (2- i7, 16Gb RAM, Win7 Ult/ 1-i5 laptop, 6Gb RAM, Win 7 Pro/ 1- core2duo, 2Gb Ram, Win7 Pro); all computers have had the entire FULL download of the latest set of drivers and software (multiple times!) but they keep dropping the drivers and I"lose" the printer on one or more machines about once a month or so.
You can print something and shut down normally, come back the next day and start up the system , try to print and get a message that the printer is 'off-line" or the scaner is in use by another machine (the computer i am on when this message comes up is usually the only one that is on and was the last turned off the day before).
I have run diagnostics from HP with nothing found; I have checked my system settings to see if anything is showing up in the logs if any changes are being made to cause the issue and come up empty. The problem occurs seemingly randomly; things will work great for several weeks and then one or another of the computers will stop printing and I end up re-installing the drivers.