I had the same problem. It was caused by the Skalp plug-in. When I removed the Skalp.rb code in the plugins folder, SketchUp Pro 2017 would start again.
I had Skalp running well with SketchUp Pro2016, but when I upgraded to SketchUp2017, Skalp admitted that their old plugin was incompatible with the new SUP17 version.
They have published a new version of their plugin in January 2017, but it still crashes Sketchup Pro 2017, and they have not (yet) been able to resolve the failure. Support told me that only three other users had reported it to them, so their priority had to be elsewhere.
Too bad, because I found Skalp really useful for rapid generation of clear construction diagrams.