What do you do when the off/on button doesn't respond. It is on and I can't get it to go off.

[jvwalk]

Using HP Photosmart C5550 with a Mac OS X 10.6.8.  Error Message shows B00788FE after last night B807BE88.  Printer registers as "off line".  Have tried unplugging, it reset, worked once, then it is back to unresponding.  Nothing new was installed when this problem started out of the blue.  Printer purchased July of 2009

[ShlomiL]

Hi,

Please temporarly unplug the USB from the back of the printer, then follow any of the steps below:

http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00489814&cc=us&dlc=en&lc=en&product=3577718&tmp...

If the same persists, I would also recommend you to try plugging the printer to a different power socket with no use of any power hubs.

If any of the steps will not resolve the issue, It worth trying removing the ink cartridges and checking if the same issue persists or not.

Such an error can be caused by a damaged ink cartridge as well, beside those I affraid you will need to service the product.

Regards,

Shlomi

[jvwalk]

Good suggestions, however, none worked.  The green power light is still on, but printer is not responding in any way.  I've unplugged, and replugged, and tried all the steps recommended with the print cartridges.  Printer seems to be dead.    Tried using a different wall outlet.  Servicing may be the next step or replacement of printer.  

[SeanS]

I would go ahead and call support and see if they can help you anymore. If your in the US you can call: 800-474-6836

If not you can get find your counties 800 number here: Contact HP

Good luck!