Hope you don`t mind me chipping in Phill,
@ Crispyt, can you check that the CPU fan is working correctly if at all + as an outside chance do you have an alternative keyboard you can try?
The specs for your computer list a 180W PSU which is low by todays standards, due to the demands constantly made on PSUs they are often the 1st component to show signs of stress and to test them comprehensively the services of a tech are required due to the specialist equipment used to simulate a PC working under load, how much and what type of use has/does the PC have, work, gaming, internet etc, this info helps to identify if a component may be weakening/failed.
See here http://h10025.www1.h...en&dlc=en&cc=us
for how to remove the PCs side panel and some other display troubleshooting.