1) Verify that the srcscanner.exe executable exists.
The srcscanner.exe file should be located in the install under bin/unwrapped/win64.o as indicated in the error message.
If the file or folder has been erased by accident, it should be restored.
A full reinstall is likely the safest option in this case because it might not be obvious what other files have also been removed.
2) Check the search path used by Vivado to make sure that the Vivado/bin/unwrapped/win64.o directory is included.
To do this run the following command in the Vivado Tcl console:
3) Check the search path for colons (':') being used as a path delimiter.
There is a known issue in Vivado 2017.2 where the header.tcl file will prepend the PATH with the location of 3rd party simulation of synthesis tools using a colon as a delimiter (Windows requires a semicolon for path delineation).
This script has been corrected in Vivado 2017.3.
If there are colons (or other unsupported path characters) used in the search path they should be fixed in the Windows Advance System Settings.
If the colon was introduced by a Xilinx setup script, use the following command in the Tcl console:
set env(PATH) <new path>
Where "new path" is the path obtained using "puts $env(PATH) " but with colons changed to semi-colons.