What problems did you have with SU17?
Did you run Checkup - a new computer check app released with SU17 that poke around in your computer to see if it’s SU17 ready.
Laptop or desktop? By default laptops use the integrated Intel graphics chipset. Users have to adjust the setting in the graphic card control panel to use the more powerful cards.
2017 not launching contains links to help with some of the common issues, like needing to update the graphic driver - have you updated yours?
As mentioned above, unless you uninstalled SU15, it’s still there. And if you keep the installation files, you could reinstall SU15.