Hi Everyone,
I'd just like to say thank you for all your help and that the probelm is fixed now. In the end I paid someone to sort it. He explained it was something like the permissions to some of my files were held by my old operating system and after my computer crashed and I had to put throught the recovery disc these permissions were lost. He told me he had a program that searched for the old permisssions and re-installed them.
Thanks.