Question Author
Sorry Rojash.
The Stop Codes that I see include (last few characters only): 00A, 050, 0C5,
024, 01E, 0D1, 07F, and error messages include "IRQL_NOT_LESS_OR_EQUAL" sometimes with the word "DRIVER" in front, and "Run the driver verifier against any new or suspect drivers. Try enabling special pool"
As I said originally, this problem occurred suddenly last week. The PC is only 4 years old and I would very much like to be able to get it going again rather than splash out a lot of money for a new one.
I would be very grateful foe any help you can offer.