Problem occurs when pressing the @ and the " keys. They seem to be mapped to each other, so @ -> " and " -> @. The system preferences allow modifier keys to be re-mapped but not these two. Can it be done?
That sounds like the main difference between a US and a UK keyboard. On a UK keyboard the " is above the number 2, and on a US keyboard the @ is above the 2.
Is the keyboard UK or US?
And is the Mac set to have a UK or a US keyboard attached?
use keyremap4macbook. It adds all these options and it's easy to add new mappings on your own - eg for media keys and so on. Also you can make the remaps device specific so a mac keyboard will work as usual.