I've been playing with this issue for a while now and I believe I have tried all the solutions offered within the new and old forums and still have not been able to make a decent color print.
The colors do look good but there is also a crosshatch in black within the colored prints.
Some specs to help diagnose:
foo2zjs released 2006-12-23
$ uname -a
Forum: HP Color LaserJet 2600n