Im getting additional numbers with some of the letters I press, for example F shows 5F but if I hold the F key down it will perform as normal. This is not for all keys though, can anyone help.Cheers

Have you checked your keyboard settings. You never said what OS so I will give you a gerneic placement of this option:
1. Go to the Control Panel
2. Click on "Regional and Language Services"
3. Click on the "Languages" tab
4. Click on "Details"
5. Click on "Key Settings"
6. Select "Switch Between Input Languages" and click "Change Key Sequence"
7. Make sure all the boxes are unchecked or unassigned.
8. Do the same thing with "Switch to... (Keyboard type)"
9. Click "OK"
10. Click "OK"
11. Click "Apply"
12. Click "Ok"
13. Reboot

Let me know!