Hi guys. Thanks for all of your replies and help.
mwe99 - I would have tried your suggestion but it was a bit late and I would have awakened the whole house
DJex - this is what I tried and luckily (touch wood) it has worked fine so far. All of the keys are working and none are sticking.
brian - I actually found that tutorial also, and it seems quite helpful although based on a PC keyboard. Luckily the problem was solved so didn't have to attempt any 'surgery'.
ipab - It's a Dell Inspiron 6000 and I've only had it a few months so therefore it's still under warranty. So if it proceeds to mess up in the future I should be ok.
Thanks again