Please gather both these two informational files, and attach them here:
...\Steam\steamapps\common\Cities_Skylines\Cities_Data\output_log.txt
DXDIAG is a program you run from a command prompt or the Windows start menu 'run' dialog box (or 'search programs' in Windows 7 or later). After running it will open a window and start collecting info with a progress bar in the lower-left corner. When it completes click the 'save all information' button and save it to a file then attach that file here.