I had a scary experience today. Last night I went to a government site to get some information. It had at least 2 transcription errors. Apparently, the errors were some sort of malware. When I attempted to start the computer this AM, I was unable to get it to operate at all beyond the initial screens. A neighbor showed me how to reset the cpu to its status several days ago using system restore. The machine is back in operation.
If you have not done this exercise, do it now so that when the problem hits you, you will know what to do. It's simple if you know what to do.