Black prints as gray from Photoshop CS3 or Acrobat Pro?

I'm working on a Macbook with Leopard, using CS3. I recently started using a HP Officejet Pro K8600 printer (inkjet, CMYK cartridges). My problem is that when printing out of Photoshop and Acrobat, any black items are outputting as gray- I'm assuming that the printer is creating a composite black out of the color inks instead of using the black ink cartridge (?). This is not a problem when printing out of Illustrator (blacks look great). Any ideas?

I have tried running Photoshop in Rosetta mode, deleting the Preferences file, and several different print and Photoshop dialogue settings. Photoshop, Acrobat and the printer driver are all updated. I'm running out of options and Adobe technical support had no solution either. Any advice is greatly appreciated!

Black prints as gray from Photoshop CS3 or Acrobat Pro?antivirus downloads

I am only guessing since I'm new to MAC Leopard. I have a sneaking suspicion that your thought about Photoshop and Acrobat creating composite black, instead of using the actual black, could be true. It seems to me that I saw some printers that don't use the same black cartridge for both text and photo (which is aggravating). My guess is that with that printer, there may be some photo specific cartridge that it may want you to switch to when printing pictures. It's some weird way that the printer and computer work together. Maybe someone else reading this could elaborate more on this or perhaps has another idea.