I've found the log entry for running Chckdsk in Vista.... (excuse my keywording) Windows Vista checkdsk results event log
Open The Event Log...
Control Panel (Classic View) -> Administrative Tools -> Event Viewer (3rd choice)
The ChkDsk Log is found in....
Windows Logs (2nd choice on left) -> Application (1st sub-choice)
< NOTE >
This will display a number of information logs in the center pane, many of them from the most recent Windows startup. You will notice the 1-2 hour time difference in events if you rebooted to scan (time spend runnign chkdsk). This should help you identify the startup events after the scan...
About half way down the list of logs, look for the item Wininit in the source column. This will contain the log data for the ChkDsk scan prior to the boot.