Had a similar problem with my hp psc 2175 all-in-one.
My solution did not cost any money. Just a few Q-tips and some water or alcohol.
If you open the printer the cartridges slide to the middle. Push them further tot the left. Then look in the printers inside on the right. That is where normaly the cartridges rest in power off mode.
I spootted a "notch" there all covered in ink.
If you see the same, that will probably cause the problem.
I cleaned that part and also the connectors of both the catridges and the printer with a few Q-tips with boiled water or alcohol.
Removed the power cable, plugged it in and switched on.
Then came the request tot push the button tot align the cartridges.
After that, it worked properly again.
Jacques
May 2011