Maybe it worths a Try to run rFactor "as Administrator".
I know that many Problems with every kind of Software are caused by the Windows UAC, since the default Setting of it don't gives the User "full" Rights.
And i can not tell you how to run it "as Administrator" in Windows 10, because i don't use W10.

In the past you just had to rightclick on the Programs Shortcut Icon and select "Run as Administrator" from the opening Dropdown-Menu.
Or you could set it permanent in the Shortcuts Properties.
Or, what in my Opinion is the best Solution, to set the Windows UAC to the lowest Level as first Action, everytime you make a fresh Windows-Install.
But i'm pretty sure that someone else or "Google" will tell you, how to run rF2 as Administrator in Windows 10.