I need help!!!

I am creating an Excel worksheet (XP) and my settings seem to have changed.

when I select an individual cell, Excel is selecting several cells at the
same time, as if I have the Shift/Control key down at the same time, even
though I don't?? Also, when I have the caps lock on, it prints lower case
and vice versa.

This has only just happened, I have been using Excel all morning.

What can I do to rectify it???

Any urgent help would be appreciated.

Thank you.

Louise