.. Hack the computer

Eject the disk, first. It contains the virus.

Now, there must be someone who can help you with the floppy.

Give the disk to Raxa. She is in the subway train on the darkside.

Your task is to switch all the red skulls to green smiley faces. When you click on a tile it will toggle all the neighboring tiles, too.

Put it into the computer to solve the case.