HP Imaging Device Functions causing errors on LAN

[fixpertise]

I have 4 computers on my LAN.   For months now, I have been seeing errors on the Ethernet interfaces of 2 computers  (netstat -e). The errors occured at regular intervals and seemed to be asscociated with the HP Printer SW associated with the Photosmart C7280 which was configured as a network printer.     (TCPVIEW showed  the only network connections being made at the time errors occurred were to the printer.)    The performance of the Internet  Explorer  was poor and as other networking activities such as sending e-mail were very slow.

 When booting the machines in Safe Mode with Networking,  the errors do not occur and the performance if IE was significantly better.    I finally got around to investigating this.   My first attempt was to turn off all printer shareing to stop communciation between machines.   This made no difference.    However,   as soon as I uninstalled HP Cutomer Participation Progam 10.0 and HP Imaging Device Functions 10.0 and restarted , the errors completely disappeared.   IE 8 ran like a charm and email clients stopped reporting errors when sending.   I suspect the problem is related to the Digital Imaging Device Functions but I am reluctant to reinstall lest the problem reappear.

Does anybody know the root cause? 

[Wi-Fi-Guy]

What type of router to you have and how is it connected to the internet (ADSL, cable-modem, FIOS, etc)?

[fixpertise]

My router is a Dlink DIR-655 connected to the Internet via a cable modem.    The problem described actually has nothing to do with Internet access or the router.   Several things:  (1) The errors occur on only 2 of the four machines on my LAN, both of which were running HP Imaging SW.   (2) The errors occur when the machines are not being used and I.E. is shut down.  (3) The errors seem to occur when the HP Imaging SW is contacting the Photosmart printer.   On a virtually idle machine,  I have watched the TCP/IP traffic with TCPVIEW and could see  the svchost.exe which is running the HP Net Driver (HPZ12) make a connection and the error count jump up.    When I un-installed the HP Imaging Device Function 10.0,  This driver did not start and the errors went completely away.   I haven't yet looked at this with a sniffer,but I am guessing some sort of retry logic quicks in and slows down the TCP/IP stack. until the error is cleared.

[fixpertise]

After further investigation, I have narrowed this problem down to the Pml Driver HPZ12 service    By disabling this service and rebooting, the problem with errors appearing on the LAN interfaces go away and browsing the Internet is fast. 

Along the way I noticed several things.   This problem may be related to the specific Windows Version or aggravated by other SW installed that uses the network.   I installed the complete suite of All-In-One Printer SW (V 10.0.1) on a freshly installed and updated XP Home Edition (SP3) machine with no other SW installed and  no errors occurred on the LAN interface even when I left the system running for days.      However, I un-installed and re-installed the same SW on an XP Professional (SP3) machine which has AV SW, Skype and other SW that uses the network  and the errors appear as soon as the Pml Driver Serv ice starts after booting.  If I disable the Pml Driver Service and reboot, there are no errors.   Now  here is the weird part.    If I manually stop/start the Pml Driver Service, I do not seem to get the errors.

If the Pml Driver service is enabled so that it starts automatically,  you get the errors, but typically the count grows to between 50 and 100 and then stabilizes.   However, if a program like Skype (which also uses UDP) starts automatically at the same time the Pml Driver service starts, then you get many more errors and the number keeps growing over time.  My guess is that the Pml Driver has a bug in its initialization but I cannot guess what it might be?   Port conflict?