I am unable to defrag my C: drive. When I push the defrag button. An error message pops up saying, "Disk Defragmenter has detected that chkdsk is scheduled to run on the volume C: Please run chkdsk /f." However, when I run chkdsk /f. it says "the type of file system is NTFS. Cannot lock current drive" and "chkdsk cannot run because the volume is in use by another process. Would you like to schedule this volume to be checked next time the system restarts? ." When I select yes and restart my computer, it gives me a brief blue screen saying something about being unable to check the disk because the files or volume is NTFS. What can I do to be able to defragment my system?