strange problem in outlook 2007...

For some reason, one of our users suddenly cannot reposition the cursor in emails by using the arrow keys. The delete key does not work, either. If he wishes to reposition the cursor, he has to use the mouse. The backspace key DOES work. He says that this problem is exclusive to outlook, and thinks he inadvertantly changed a setting, but I can't seem to find one that applies. Any ideas?

Thanks in advance!!