One of the most useful tools in Windows Vista is without a doubt the System Restore tool. This handy little feature can roll back your system to a previous point in time, potentially eliminating any problematic errors caused by a recent change.
System restore points are created automatically (during installation or new updates/applications), however you can create your own should you wish. It should be noted that documents, photos, e-mails and other such items will not be backed up or restored - only major system settings and applications.
To open system restore, run "rstrui" from the run menu (Press WINDOWS KEY + R to access this). You can either restore the most recent backup, or select from an older restore point. Once you have made your selection, click next:
You will then be asked to confirm your selection by checking the details and clicking next:
Your system will then restart and roll back the system to how it was at the previous restore point. Hopefully fixing the problem that necessitated this action. You are given the option of undoing the system restore option if you so wish.