The dialog box says the printer is offline - Canon PIXMA MP600 all-In-One InkJet Printer

Is the printer directly connected to the computer by the USB cord or do you have it connected to a print server (or router with a print server feature) or a USB hub?

Make sure that the printer is on. Make sure that the printer isn't offline in the Printers Control Panel. In most versions of Windows OS, go to the Control Panel > Hardware and Sound > Devices and Printers (Printers and Faxes for XP; the previous subcategory may also have a slightly different name). Look for the MP600 and left click on it. Check the status listed below. Right click and attempt to make the printer the Default printer if it isn't the default printer. Check the Printer Properties and that the correct USB port is assigned (the Ports tab).

If you are using the direct connection, check that the cable is connected to both the computer and the printer. Try another USB cord (A male to B male). Make sure that the cable is 6' long or shorter. Try using a different USB port. (Port failures do happen.) If the printer still is listed as offline, check the device manager. In most versions of Windows OS, go to the Control Panel (details below if needed) > System and Security > System or Printers and Sound > Device Manager. Scroll down to the line Universal Serial Bus Controller. Expand the line and look for a yellow triangle with an exclamation point or a red triangle with an X. Right click and attempt to update the driver. If that doesn't work, try to uninstall the driver (right click again). Then restart the computer. Wait to see if the correct driver is installed. (Check in the device manager again.)

If this still fails, try using a different computer to check if the USB port has failed on the printer. If a second computer won't talk to the printer directly, contact Canon if the printer is under warranty. If the printer is out of warranty, decide if the cost of service is worthwhile for you (minimum of $50 just to diagnose the problem plus shipping). If a second computer works then consider if the computer is under warranty. Contact the manufacturer for service in that case. Otherwise, if you have a desktop with free slots for add-on cards, consider putting in a USB card (PCI or PCIe) and check if that helps. Replacing ports on a laptop requires a new motherboard unless you can use a PCMIA USB card.

If you have a USB hub or print server in use, try a direct connection to the computer. Replace the hub with a different one. Try a USB hub that has an AC power cord plugged in. Some USB ports can't provide from the computer to the hub and then the printer. Multi-function printers are even worse with bad USB cables interfering with their communication. Swap both USB cables during testing if possible.

If you use a print server, test the direct connection as well. Again try a new USB cable. Check that the server and router are communicating. If my ISP's modem doesn't connect to the upstream server, my router will not run any devices on the network. (This is due to problems with the Dynamic IP addresses (DHCP). Check that you have the correct program installed to run the print server (if needed). Every time I reinstall the OS, I need to install the printer as a local printer. Then I can connect the printer to the router and execute that device software to properly route print jobs.

Note: my Windows computer says the printer on the router is Offline. However, the printer works after I get the "Printer error" message for each item sent to the printer.

Accessing the Control Panel for Windows versions prior to Windows 8, click Start and look for the Control Panel in the right hand list. With Windows 8, in the Desktop mode, press the Windows Key + C (or hover your mouse cursor in the upper right corner of the screen) to open the Charms menu. Select Settings and then the Control Panel. For Mac systems, you would need to use the appropriate system tools.

I hope this helps.

Cindy Wells
(I've found bad cables/USB hubs to be the problem most often.)

Unplug the printer from the power. Turn off the computer and then restart the computer. Plug the printer back in. Let us know what it does.