I started getting checksum errors in 15.01 R9 after upgrading from R8 as well. I'm using Win8.1 and printing via USB to an Ultimaker Orginal. I'm able to save the gcode generated by R9 and print without issues using Printrun.
Before reading anon's post, I thought it was communications related and tried the following to isolate the issue.
-Uninstall and reinstall arduino driver
-Reflashed the Ultimaker with the firmware in R9 and the version on Ginge's marlin builder.
-New USB cable
-Uninstall all version of Cura (checked registry and Program Files) and reinstalled R9