It did happen after updating the DATs. I found something on Mcafeehelp.com that said:
"The reason for this is the update or upgrade does not finish setting up until Windows finishes restarting. Sinch this message appears when Windows has not finished restarting, the update or upgrade has not been fully set up."
I went into the Windows Registry and under "DATFile" I changed it to a previous DAT file number so the virus update will think the DAT I installed has not been installed yet. Then I reinstalled the update and the error went away. The last update I installed was 4122, so I changed the registry to 4121.