Blinking shortcuts have also been connected with malware / virus. No panic, I would say, but a complete scan with your AV would hardly harm, as well as one with Malwarebytes.
Is it your drive going busy, or is it your CPU - of course, these are related? You may have some background programs running? This you can check by pressing Ctrl+Alt+Del > Start Task Manager
You can also manage your starting programs with
http://www.snapfiles.com/get/startdelay.html or other similar software. They delay the startup of secondary programs - but I'm not sure this is your case. It depends...
Anyways, best of all.