Open Explorer and right click the volume that chkdsk is scheduled to run on (the partition you added) | Select 'Properties' | 'Tools' tab | Error-checking-->'Check Now' button | Under 'Check disk options', put a check next to 'Automatically fix file system errors', and click the 'Start' button | A disk check dialog will pop up asking if you'd like to schedule the disk check to occur the next time you restart your computer... select Yes | OK out of the Disk Checking windows, close Explorer, and restart your PC. I've found that this procedure, as opposed to running chkdsk from the command prompt normally overrides the dirty bit.