I got a Dell notebook and recently when boot up the screen goes black except for the mouse. When I press Ctrl-Alt-Del. The task manager come out and I have to switch task to go into Window. Is my window infected by virus or corrupted? Appreciate to anyone who can help.

Is my window infected by virus or corrupted?

maybe it is a virus. i had experienced this and i had to do system restore. during the black screen, open task manager, select application tab and click new task... type explorer.exe.

download and install Malwarebytes' anti-malware.
download and install hijackthis and get a log from it. post it here.

can you get in through safe mode?
(keep pressing f8 at start up)