A friend suggested I contact a laptop repair shop in Stockport. I did and they thought it was probably the fan. I took it in and they fixed it there and then but not before there was another scare when they booted it up and there was no display.
After some head scratching the engineer realised he had not reinserted the RAM!
But one more headache to fix. I launched Cumulus without first checking the system date. It had reset to August 2008 as the netbook had been reset. Bugger! Another 15 mins fixing various files and then it was okay.
The shop is a godsend as they sell hundreds of various second hand PCs so when the day of reckoning does arrive I have somewhere to buy a replacement instead of the dreaded Fleabay!