HP LaserJet P1102w will only print wirelessly if I turn the printer off and on again

Question

I have 2 Laserjet P1102w that work fine printing through USB.  However, I was hoping this printer could become the standard wireless printer for individual users in the office.  I have setup 2 different printers wirelessly with their own static, reserved IP addresses and they are connected to our wireless access point (WPA).  We have  all laptops that are connected to the network via the same access point as well as through hard wired ethernet.  In all cases, they are on the same subnet.
Once I connect any laptop to one of these printers wirelessly through either the "smart install" client or the latest regular installation exe off of HP's site, it will print fine initially.  However, whenever I undock the laptop or even just wait a few hours, the connection will be lost and I cannot print.  The queue just says "Error - Printing" when I print sometihng.  No errors in the logs.  The connection will come back if I turn off the printer and turn it back on.  This is very annoying and will probably not be acceptable to the users.
So I wanted to do more testing and connected both printers to my laptop wirelessly and made sure they could print successfully.  I opened 2 command windows and ran a ping -t on each IP address to see at what point the connection dies.  The ping will reply until I undock and go from hard wired / wireless to just wireless.. then it will say "Destination unreachable" and I can't even access the web interface. Even if I redock to hard wired / wireless, I still can't print unless I restart the printer.
This happens on 2 different laptops with 2 different p1102w printers.  Any clue as to what's going on here and how I can fix it?
Edit:
If I have both wireless and nic enabled, once I undock the laptop, the ping -t changes from replying to the ip of the printer, to replying to the address of the wireless adapter with "Destination host unreachable".
For example:
IP of printer: 192.168.2.95
IP of wireless adapter on laptop: 192.168.2.25
ping 192.168.5.95
Reply from 192.168.2.95
Reply from 192.168.2.95
*undock"
Reply from 192.168.2.25 Destination Host Unreachable
Reply from 192.168.2.25 Destination Host Unreachable
This does not happen if I disabled the nic and run only off the wireless card.  So the workarounds are to either turn the printer off and back on if I undock every time, or disabled the nic.
At this point, I just want to understand why it is like this?

Answer 1

Mowaffaq, you may want to determine whether you are making those changes in the master printing preferences (versus the adjusting the session printing preferences from within your application).
Click "Start", click "Printers and Faxes" (or "Devices and Printers"), right-click your printer, and select "Printing Preferences". On the "Paper/Quality" tab, you should be able to specify A4 as your default paper for all future print jobs.
Hope that helps.