since I installed PS cc 2014 every time I launch PS is will bring up the Welcome Screen after the desk top appears. It is of no use to any even medium exp. user... and is a wast of time and resources !!!
There is a checkbox at the bottom of this screen that will turn off the screen. (you may have to scroll down to see it).
It's a training tool for those new to PS.
Because its new and its default is to open on start up.. There is an option at to bottom to turn it off. Use it and it will not open by default in the future.