First of all try running the cleaning program on your printer. In most cases the printing heads will be cleaned and a testpage is printed. This way you can determin if the defect is in the printer or not. (This is in the case in most of the times)

If the printer printsall colors C,Y,M and K (and in some cases Light C, Licht Y and Light M) fine, then your problem lies probably in the driver. Are you using the correct driver (correct brand/type and model) and are you using the latest drivers? Are the driver settings correct?

If the above are all ok, does the problem occur with only one application or are there other applications that have the same problem? Are there any programs that print good?

As for ink-usage: A lot of consumer-type printers use all colors even when printing in black. That is the way they make money, since they practacly give away their printers for free.

Mike
www.mikewever.nl