What do you mean by "obvious things" please because I don't want to give you suggestions and you just reply back with did that; tried that etc
What OS is our computer running please?
I have deleted the old HP printer file and also taken off the Canon mini Photoshop file.
Internet Explorer, and Virgin Media
Ok click the start orb on the bottom left corner
Click on "Devices and Printers"
Right click your new printer listed under "Printers & Faxes" and choose "Set as default printer". Then click Ok
But I have done that and it is already set to Set as default printer, when I tried it out it was just the same ie Still looking for HP C5100 All in one printer.
If you go into the Photoshop printer settings can you select your new printer from the pull down menu?
What is happening is that the Canon Printer is being selected for the printing but the scanning is asking for the old HP printer!