Maybe its a bug if it print gray?
Its a report in Turkish about it here:http://bugs.pardus.org.tr/show_bug.cgi?id=16034
Maybe you could fill in some comments in english there to.
Or just write a new report in English.
If buy a new printer I can recommend this list:http://www.openprinting.org/printers
Go for those with 3 penguins.