HP Officejet Pro L7555 partial network connection issue

[DJLim]

Hello. I've got a rather interesting (and frustrating) problem with a printer connection.

The Setup

My Officejet Pro L7555 has been in use and has run fine for the last 3 years or so. It is connected to my home network via an ethernet cable directly linked to my router. I have a Win XP desktop, a Win 7 laptop and a Macbook Pro connecting to the network via WiFi. I have the printer set up to 192.168.0.200, which is outside of my DHCP range so that it is not impacted by router cycling.

The History of the Problem

After one print job a few days ago, it went offline and refused to come back online. I tried just about everything, from resetting the whole network and every computer connected to it, rebooting the printer, even resetting the IP address to DHCP and then resetting it to 192.168.0.200. The odd thing is that I can access the printer's web page via a browser, but no matter what I did, I could not connect to it to print or scan. I ended up removing the printer via Windows Control Panel's Devices and Printers page. I then could not re-add it via "Add a Device". 

I finally downloaded HP's network and printer diagnostic tools, as well as the full driver and utility pack (HPHNDU, HPPDU and OJProL7X00_Full_14, respectively). Both the network and printer utilities say that the printer is on my network. When I try to install the drivers, it gets most of the way through, then throws up an error screen that says that it *MAY* have a connectivity issue, and that it cannot read the printer status information (something to do with the ink cartridges). It also asks me to make sure that UDP Port 161 is open. 

I have gone to  Windows Firewall and added a specific rule to open UDP Port 161. The program still refuses to finish installing and gives the same error.

The Partial Fix

I have the option of going ahead with the installation while ignoring the error. I have chosen that, and I can now print. However, I cannot scan. The printer cannot seem to find my computer anymore. 

Can someone please help me? It is incredibly frustrating that a perfectly good and working setup decides to go belly up for no reason one day.

[Binary_Zen]

Do you remember if there was any software that was added or updated when the printer driver lost connectivity? 

[DJLim]

Not to my knowledge. There was no update pop up, nor did I manually update my drivers. I simply ran a printjob. When I went to print another job, it went offline and the fun began. 

[DJLim]

So... any advice? It's still not fixed, AND it has presented with a new problem. 

Tonight, the printer crashed. It just stopped working. None of the buttons were responding, including the power button. I had to do a hard reboot by pulling the plug. At that point, it came back, but seems to have lost the duplex printing feature. I can now no longer print double sided sheets. The duplex unit IS plugged in at the back of the printer. I have unplugged and plugged it back in. It still refuses to print double sided sheets. Also, after every two pages, it says it is out of paper when there is a whole stack of paper in the feeder. I have to sit there and press OK so that it will go on and print the next two pages, then say it is out of paper again. 

Can someone PLEASE advise? I'm getting pretty fed up with this printer, and have received NO helpful response from this support forum so far.