Comuters problems can be quite complex and so it hslps if you put a little more information - actaully quite a bit more information. Therefore i have to assume that: you are in the UK, have a UK English keyboard and are running Windows XP.
If you have a UK keyboard then then upper case 3 will be marked as the UK currency symbl (Pound). If it is a US Keyboard it will be marked as the 'hash' symbol (Often erroneously called the 'pound sign' by US English speakers.)
If your keyboard is UK and you are geting a hash sign even though it is marked with the pound sign. Try: Start, Control Pannel, Date Time Regional Options, Regional Language Options.
Terry, February 2006