keyboard issues

A weird thing has started happening with my laptop. My cursor keys have combined roles, or something - whenever I press the down-arrow, the cursor jumps down AND right: same if I press the right-arrow. This is incredibly annoying, cos I'm working in Excel at the moment inputting pitch and duration measurements for yet another batch of sound files, and it means I can't use the arrows to navigate around half the directions I need. It's not so much fun editing text documents either. This is probably an indication of how I should work at the office with a desktop maintained by real live tech support, rather than lurking in my "home office" with nothing but an internet connection to any outside world. Hmm, once my hair's dry, maybe I'll do something about that.