"HP Toolbox - IT Professional Use Only" AVOID!
Don't know if this is something that's restricted to the K5400 but somehow I doubt it..
I made the mistake of installing this piece of *$%£ software thinking, mistakenly that it was the same as the K550 toolbox for monitoring and handling maintenance tasks. Oops... apparently not.
This [irony] useful [/irony] nugget installs itself without providing any add/remove entry so you can't get rid of it except through using their scrubber utility and then it has limited effects if you're not careful.
The net result of installing this thing is that your machine will insist on installing any of the printers it covers as soon as it detects them on the network... I think it does this through a service called "HP Network Devices Support" so I've disabled this.
Perhaps the most annoying aspect of this thing is that it will insist on re-installing the printer using an HP standard TCP/IP port (assuming you're using a networked printer obviously), ignoring any standard TCP/IP ports you are already using.
If pushed I would actually characterise this piece of software as right up there with the Sony rootkit because I simply cannot get it uninstalled properly and HP are naff all help..
So, be warned... avoid like the plague.