Please try the following. (Helped me with Turbotax 2017 on Windows 10.)
1) Disable all virus and firewall software.
2) Uninstall Turbotax.
3) In Regedit, delete all keys that contain words intuit or turbotax.
4) Untick 'Load startup items' in Msconfig and reboot.
5) Reinstall Turbotax. After updates you can restore your sysconfig, firewall, etc.
I believe this helps with quite a few similar Turbotax loop situations. Since registry editing is the most time cumbersome operation here, you may skip part 3 on the first try and see if it works without it.