Hotpoint Aquarius CTD00 - 'empty water light' constantly on!?

Help! My Hotpoint tumble drier has decided to be temperamental and not dry my washing...a few days ago the 'empty water' light came on and after giving the vents, etc a through clean out and putting drawer back in, the light has stayed on! There's definitely no water in the drawer at top of machine that I normally empty out after each time I've used the machine....The machine is just under 4 years old, has been fine up until now.
Has anyone else had a similar problem or any suggestions as to what could be the matter / how to repair....??

Lisa Bell
July 2010