Hi Fred, and welcome to AF
Hmm, I don't know this, but "crosshairs" sounds like some app might be responsible rather than a hardware fault. Have you installed anything shortly before this started, and in particular do you have any screen testing apps installed? I've heard of some devices having a setting in developer options to enable something like this, so it's probably worth looking in that menu as well.
If that doesn't work it might be worth asking in the Galaxy S2 forum here.
Good luck,
Hadron