Tried the msconfig start up process, unfortunately it did not prevent the problem reoccurring, so in safe mode I backed up to an external hard drive and then ran a recovery disc which I had made when I bought the computer. This took my hard drive back to factory settings and still no joy. I then ran a few hardware tests on the hard drive and each one told me it was faulty. So I've installed a new one now and every thing is running fine.

    Sorry to have troubled you over a hardware problem but I guess one has to start some ware. Thank you for your patience and effort Richie, take care H