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Thank you neildownx. I have tried but unfortunately without success. When I typed in the command and clicked OK a black window flashed briefly on the screen then disappeared, but that's all that happened. I also turned off System Restore (not for the first time!), turned it back on again and have created just one new restore point, but will need to wait a day or two to see if it works. No problem about losing all previous restore points as none of them worked anyway. I'll keep hoping but thank you for trying.