we had no end of problems with Win7 & a HP LaserJet (1240 I think).
In the end our tame network Guru made a .bat file that re-instated the driver, but it had to be "right Click" run as administrator type thingy to have any effect.

Every so often the driver would look for all the world as if there and not functioning. I don't understand the reasons, or have access to the .bat file now. But I am positive it is the combination of Win7 and HP that causes the problem. Epson seem to have it sorted in my experience.