Last month McAfee released a corrupt DAT file (5958) that could have caused issues with Windows. The update included detections for malware variants, but falsely indentified a threat on the svchost.exe Windows system file, which resulted in your PC not booting anymore. 

McAfee have successfully rolled out the new updates, which have resolved all problems.

If you do have any issues at all, please do not hesitate to contact the Healthcare Computing Service Desk on 01425 470888.