I am definitely interested because I get quite a few complaints about the P900, second only to the HP Z3200. The Z3200 and P900 seem to be problematic: the Z3200 due to extremely buggy drivers and the P900 due to... well... I'm not sure yet. I have
proof of the Z3200 driver bugs but I can't pinpoint the problems people are having with the P900 yet.
I would suggest more ways to test it but the problem is, if it's erratic I don't know that there's any reliable way to test. If you get the problem on one print, have you ever tried just clicking print again to see if reprinting the exact same thing results in the same missing channel? Or is it random and maybe doing that would give you a good print the second time?
If the print preview always looks OK, you'd think it's a printer (hardware) issue but to be sure, if it happens in Qimage, you could always stop it via the Windows spooler and reprint immediately from Qimage: if you reprint or load the last job from the automated job log and reprint, Qimage is sending the exact same data to the printer. If one works and the other doesn't, it'd be more proof that it's a hardware issue since the same data caused two different results.
Do you always print with Qimage or are you able to replicate the problem in other software too?
Regards,
Mike