This evening I bought a new HP Photosmart C4780 printer. I am trying to print photos now and the photos are being printed with small vertical lines across the whole photo. How do I get rid of them?

Try hard-wiring your laptop to the router with an ethernet cable as a test and then try printing, if you do not loose connection to the internet then the problem is probably that the printing is hogging your wireless bandwidth.
If the same thing happens with loosing connection to the internet try connecting to the internet real quick through another computer that is hardwired, you want to find out if the problem is a wireless one or that affects wired computers also. You might need a driver upgrade, you also might need to upgrade the firmware of the router

Yes it could be the problem. Try and get a different print cartridge and if it doesn't work you may just have to get a new printer.

Try to reset printer with hp software reset utility

Some ink may have become dried up in the pinthead.
Do a couple of ink cleaning cycles may help.

Try using the HP Print Diagnostic Utility in Windows - HP Customer Care (United States - English)


If you need more help come back.Post / thumbs / testimonial are welcome!

The problem is in your printer set up. When you go to print, select the type of paper, size, horizontal or vertical print mode. If you do not designate photo with size and paper type; it defaults to standard 8x10 paper from the lower tray. This is all explained in your printer manual or on line at HP.com.

Shaking these cartridges does nothing except give you a little exercise. If this is a brand new HP cartridge you are having problems with I would return it to the store you purchased it from. HP brand cartridges should not give you these problems right out of the box. The print defects you are seeing are due to a dried up or clogged print head. If you like you can try hydrating the print head on a water soaked paper towel until the ink starts flowing, but there's a risk you will cross contaminate the colors.

you shoud test printhead,if they are ok, you choose "best photo" in printer property.

align the ink cartridges and clean the heads. change your printer settings when printing photos to more dry time, less ink and quality to normal

Hi,
it sounds as if you may have the picture quality set to draft, its worth a check, especially if printing is ok. Does it print colour writing well too or just black, one of the colour inks may have a block or be low, go into printer settings menu and check what print quality its set for.