Problem with HP Deskjet 3940 as a network printer

Hi, i have this printer connected via USB to my Asus WL600g router (printer
is supported by this router). Everything works fine on PCs with Windows XP
(2x) or Windows XP 64bit (1x) , but on Windows Vista (2 computers) i have
still problems... when i try to print something, printing starts, but it
stops in the middle of process and on PC i see "Error" message in status of
printer. If i connect this printer directly to PC, it works fine. I tried to
use drivers for XP, but it didnt help, i tried to contact HP support, but
they told me that they dont have yet group for supporting Vista, i tried to
restart modem and PC lots of times, reinstall printer, download all updates
for Vista but nothing helps...
I dont know what else can i do... any advices?
(And sorry for my engRish )