Windows Vista includes a utility that will scan your system for corrupt, changed or missing system files. Running this from the command prompt is much easier than booting off the DVD into repair mode. To run this utility, you will need to open a command prompt in administrator mode. You can do th0at by right-clicking the Command Prompt in the list and choosing 'Run As Administrator'. To scan and attempt to repair any files that are changed or corrupted, simply run the command 'sfc /scannow'.