The windows cannot find logon.exe error message

Hello, I am not sure this is some sort of virus or malware but it seems that I will be getting the error message "windows cannot find logon.exe" upon starup and I'm trying to get rid of that. This is the first post I ever make and if you cannot help with such matters I'm sorry to bother.

When I started my computer this morning I got a message from AVG free edition that a threat was detected, logon.exe. I clicked on "heal" and it seemed everything was fine but when I next tried to open my computer and every time I do, I get the above error message. Also, it seems sometimes my computer has trouble booting at all, with monitor remaining black and the cpu apparently silent. That problem occured well before i first got the threat detected message by AVG. Usually when this happens I simply keep trying to start it until it finally works. I'm not sure it has anything to do with logon.exe.

Is there anything I can do to get rid of the message when windows start? Is this a known undesired program? Thank you for you time and help.