Windows Vista: The Complete Reference (Complete Reference Series)

The ChkDsk (Check Disk) program can both diagnose and repair errors on a wide variety of devices, including hard disks, floppy disks, RAM drives , removable disks, and laptop memory cards. ChkDsk doesn't work on CD-R or CD-RW discs. ChkDsk can check the physical surface of disk drivers for bad sectors and possibly recover lost data, and it checks the file allocation table (FAT), the directory structure, and the long filenames associated with many files.

Windows Vista comes with a feature called Windows File Protection , or WFP. WFP is running whenever Windows is running, monitoring the files that make up Windows itself. Whenever a program replaces one of the Windows system files, WFP checks whether the new file was accompanied by a "signed" ( verified and encrypted) file from Microsoft. If not, or if an earlier version of a file has replaced a later version, WFP replaces the file with its own copy (from the WFP collection of duplicate files at C:\Windows\System32\dllcache, if Windows is installed on C:).

You don't have to turn WFP on, and there's no way to turn it off. WFP doesn't display any messages when it decides to replace a system file with its own version, but it may prompt you to insert the Windows Vista CD-ROM to reinstall a file.

Running ChkDsk

Certain ChkDsk functions, like fixing disk errors and recovering lost sectors, are not accessible while Windows is running. This is because the repairs cannot be completed while there are open files on the disk to be fixed. When you try to run ChkDsk, Windows might need to schedule the program to run the next time you restart Windows instead. To run ChkDsk, follow these steps:

1. Right-click the disk drive in the Computer window and choose Properties.

2. In the Properties dialog box for the disk, click the Tools tab and click the Check Now button. You see the Check Disk dialog box:

3. Select both check boxes to perform a full disk check and click Start. You usually see a message saying that Windows can't run the program until the next time you start Windows.

4. Click Yes. The next time Windows starts, you see a message that the disk check has been scheduled, and displaying the results as the program runs, which can take several minutes (depending on the size of the disk). When ChkDsk runs, you see its results before Windows displays your logon screen or desktop.

Other ChkDsk Options

ChkDsk can do a number of other things if you run it at the command prompt. To see your options at the command line, type the following at the prompt in a Command Prompt window:

chkdsk /?

or type help chkdsk . When you press ENTER, you see information about ChkDsk's options, which are also listed in Table 35-1. Some switches work only on NTFS partitions, and some work only on FAT32 partitions.