Hi Curious53,
I understand you have a Photosmart B8550 that is shutting down pretty frequently. I will certainly do my best to help you with this.
I would recommend that you have a look through this The HP Printer Turns Off Repeatedly and hopefully some of the steps in that can help. Because your printer is an older one, if this doesn't help there isn't really much else I can suggest other than calling HP Tech Support for your area and inquire about the trade in and trade up program and hopefully they have something with a nice discount to offer you :)
Hope this helps, have a great day!!