Lately when I turn on my pc it's saying that i have a disk error and tells me to press ctrl + alt + del after several attempts my pc will turn on. When It turns on windows is not working properly, apps are crashing and I cant open nothing not even files. I tried to scan hard drive for errors and did a start up repair but that didnt solve anything. I have CPU : intel core i5 (quad core) 2.7 ghz RAM : 8.00 GB and OS: windows 8.1 (64 bit)