How can I force a disk check when Windows 7 reports "Disk checking has been cancelled"?

According to Microsoft support, to check if your disk check schedule is really set to make a scan on the next boot (after running CHKDSK /F /R command), you can look on Windows registry. This key (HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\BootExecute) should have the entry:

autocheck autochk * /r\DosDevice\C:

If it is just autocheck autochk *, then the schedule is disabled and you will need to run the CHKDSK /F /R, or manually change your registry with to include the /r\DosDevice\C argument.

Via http://www.sevenforums.com/performance-maintenance/71175-disk-check-has-been-canceled-reboot-3.html

1. Make sure you're going to reboot in Normal Mode. Reboot.
2. Hit F8 over and over as soon as your boot up screen appears. (The computer one, which appears before the Windows one.)
3. This will take you to a DOS-like screen. Select Repair Recovery Manager. (You may be prompted to log in as an administrator user so that you can access the Command Prompt.)
4. Form the Repair Recover Manager, select Command Prompt. This will start a command prompt window in the X: drive.
5. Enter C: to switch to the C drive.
6. Enter chkdsk /f (or chkdsk /r)
7. When asked to force a dismount, enter Y
8. The disk will now be checked.
9. Note the results and close the command prompt. (Mine couldn't save the results to the logfile, because it was on the C drive. Not a train smash.)
10. Reboot.