Pressing the delete key doesn't bring up anything either.
The computer is a HP Pavilion (a740.uk)
Pentium 4, 2.8GHz processor, 256MB RAM, 160GB hard drive, DVD player, DVD writer, Intel Extreme Graphics card.
I have since added Nvidia GeForce graphics card, 512MB Ram, changed the power supply to 550W, changed the DVD writer.
I maybe shouldn't have tried to add stuff when I don't completely understand the ins and outs but it has been a year since the last modification and its been working fine up until now.