I`m not sure why the procedure has returned that error, OK to try and get started do the following:
(Create the tool on your PC)
Download the Windows Defender Offline Tool
and save to your Desktop.
You will have to select the correct version for your system, either 32 or 64 bit
to run the tool, Windows 7 or Vista user right click and select "Run as Administrator"
Read the instructions in the new window and select "Next"
In the new window accept the agreement:
In the new window select your USB Flash Drive, then select "Next"
In the new window ensure you Flash drive is selected, if not click on "Refresh" then select "Next"
In the new window accept the formatting alert by selecting "Next"
Files will be Downloaded:
Files will be processed and created
Flash drive will be formatted and prepared
Files will be added to the Flash Drive and the tool will be created.
The procedure is finished and the Tool created, click on "Finish" to complete.
Plug the USB into the sick PC and boot up, if it does not boot from the flash drive change the boot options as required, Use F12 as it boots, change options...
As it boots you`ll see files being loaded and the windows splash screen, eventually the tool will run a "Quick Scan" follow the prompts and deal with what it finds.
When complete do a full scan, deal with what it finds.
When finished, remove the USB stick then press the Esc key
to boot into regular windows.
Navigate to the following file:"C:\windows\windows defender offline\support\mssWrapper.log"
Open with notepad and copy and paste it into a reply.