After the pre-boot error-checking (scheduled) scan of drive C: (because the screen display shimmers and getting worse), it took a while for me to locate where the log file of the scan (about 2-3 hour process) is.
http://www.justin.my/2010/08/scandisk-chkdsk-log-file-in-windows-7/
"So, you just right click My Computer … Manage … System Tools … Event Viewver … Windows Logs … Application … Then looking for Wininit, ..."