HP Deskjet 3510 and network issues

I've had a HP Deskjet 3510 for 2 years (give or take) now, and never had an issue air printing from my macbook, iPad or iPhone. It would just "sleep" and the whenever printing woke up and did it's job. A couple weeks ago, ATT brought out a new modem, of course meaning I now have a new network. It took me forever to get the printer onto the new network, but it is now. However, now when it goes to sleep, it doesn't wake up to print, and often times gives an error: error code 0XCO260000 TRTHREADSTOP C and a blinking power button. If you press the blinking power button the error message clears and then you can print (though you have to tell it again to print) HP's site (as we know) is NOT mac helpful.

I find it hard to believe the printer is suddenly malfunctioning when the ONLY change has been the new network. I have installed the driver from the original CD, and I have downloaded an updated one as well. Same problems. The only surefire way to print is plugging in the USB.

Any help would be greatly appreciated. I've even tried to totally start from scratch setting it up, but haven't been able to figure that out either. I took out both ink cartridges and unplugged the power cord for several hours, which was supposed to reset per the HP site (I think that's where I read that). Nope, it still knew the new network etc.

thank you!