Quick fault find first: Start > Run > cmd > and type
net start sysmain. If you receive a “System error 1058 has occured,” more than likely the sysmain (also called Readyboost) service has been disabled. You will need to run the cmd prompt as Administrator.
To enable Superfetch, click on Start and type in
Services.
Right-click the Services item with the cog/gear icon next to it and run as administrator.
Scroll down to
Superfetch. Right-click > properties > Startup type: Automatic > Apply > OK
ReadyBoost is now usable again. Well, it should be. Let us know.
PS. How big is the SD card/USB drive you are using?
LINK HERE.