Computer locked after log in-strange images

Hello,

Yesterday while using the net my Dell laptop suddenly shut down. When I tried to re-boot it, I got the message that it had shut down unexpectedly and did I want to start up in safe mode. I did. After a long while I got a message saying it was running a disk repair and it could take a few hours. It did take a few hours, but eventually got to the log in screen. After I log in, it takes a few minutes, but then a strange background image of black and while stylised speakers (almost like boom boxes) appears over the entire screen and nothing else. There is a cursor which can move, but does not react to any commands. My only option is to power down with the power button. Is this a virus, and if so, can it be fixed?
Thanks for any help offered.