Boot up from your Windows 7 installation disc and choose to Repair my computer. When the System Recovery Options menu appears, choose Startup Repair. If this doesn't offer any solutions, return to the System Recovery Options menu and select Command Prompt. At the command prompt, type chkdsk c: /f and press Enter. This will check your hard disk for any file errors and repair them as necessary. If the problem persists, try disabling onboard hardware such as network and sound cards one by one via the Bios. Check whether the machine still boots each time.
Failing this, delete the file. It may be corrupted, and Windows will create a fresh version on reboot. Access the Command prompt via the Recovery Options menu, then type rename c: press Enter and reboot. Though editing the Windows Registry is not nearly as scary as it sounds, making an incorrect change can cripple your system. To ensure that this doesn't happen, it's important to take the precaution of backing up part, or all, of the Registry before you proceed.
If you have a habit of leaving your computer on all the time, you'll occasionally run into the problem of automatic system reboots. These usually happen after Windows downloads some sort of important update, and will usually be preceded by a notification. If you're not around to see said notification, and you have a lot of windows or important documents open on your computer, these reboots can be a hassle.
Windows 7's Aero Peek lets you see the desktop when you move your mouse cursor over to the show desktop button at the end of the taskbar. The standard delay time for the Aero Peek preview is 500 milliseconds or half a second. Here's how to speed it up: Open the Registry Editor and go to HKEY_CURRENT_USER > Software > Microsoft > Windows > CurrentVersion > Explorer > Advanced. Right-click on the right pane and click New > DWORD Value. Name the new DWORD DesktopLivePreviewHoverTime. Double-click on DesktopLivePreviewHoverTime to open it. Under Base, click Decimal and then enter the delay time in the Value data field. Click OK, and your Aero Peek time will be set. You can set the value to higher if you're activating it too often by accident, or lower if half a second is just too long. Log off and log back on for the change to take effect.