嘗試使用bootrec /fixboot 指令修復問題，修復後您還需要執行 "bcdedit /set hypervisorlaunchtype auto" 將 Hypervisor 設定成自動啟動。

Hyper-V virtual machines do not start after using Startup Repair
http://blogs.msdn.com/b/virtual_pc_guy/archive/2010/01/19/hyper-v-virtual-machines-do-not-start-after-using-startup-repair.aspx

Checked the boot order into the BIOS
Enter WinPE mode and try to repair with commands
===============
a. Insert a Windows Server 2008 R2 installation media, and boot from the media
b. At the initial "Install Windows" prompt windows click "Next"
c. DO NOT click "Install Now", click on the "Repair your computer" link located at the lower left corner of the "Install Windows" prompt window
d. Choose the repair tool option and click next
e. Select "Command Prompt"
f. Run the following commands to check if active partition is correctly set
    diskpart
    select disk 0
    select part 1
    detail part
g. You should see the selected partition has a drive letter "C", has 100MB in size and that Active is set to "Yes"
h. exit diskpart
i. copy bootmgr from X:\windows\boot\pcat to c:\ (c drive here is the 100MB system reserved partition), reboot and check status
j. Run the following command, reboot and check status
    bootrec /fixboot
k. Run the following command, reboot and check status
    bootrec /rebuildBCD

問題描述︰Windows 7/Active Desktop with Wallpaper policy show black issue

說明與方法︰從AD派送的桌面圖片無法套用在 Windows 7的機器上, 呈現黑色的底圖顏色.

Cause:

Active Desktop is not supported since Windows Vista (including Windows 7) , Windows Vista has replaced the Active Desktop with Windows Sidebar (Now Called Windows Desktop Gadgets starting with Windows 7), which also allows components to be added to the desktop.

Suggestion:

使用下面的機碼套用底圖

a) Locate the following registry subkey:
HKEY_CURRENT_USER\Control Panel\Desktop

b) Double-click the WALLPAPER registry entry. In the Value data box, type a value, such as c:\temp\wallpaper.jpg, and then click OK.

參考連接︰

· The "Desktop Wallpaper" Group Policy setting is not applied in Windows 7 or in Windows Server 2008 R2

http://support.microsoft.com/kb/977944/zh-tw

In an Active Directory domain network environment, you apply a "Desktop Wallpaper" Group Policy setting to the domain users. However, the setting is not applied to domain users who log on to client computers that are running Windows 7 or Windows Server 2008 R2.

若是您的檔案伺服器有以下特徵，我們建議您把作業系統 8Dot3 Name Creation 功能停用。
- 同一個資料夾下檔案數量多，像是超過 100,000 個
- 檔案的命名方式有同樣的邏輯性，舉例: 檔名前六個字元都是一樣的。

有這樣 File Structure 的伺服器您可以把作業系統 8Dot3 Name Creation 功能停用。
將 8Dot3 Name Creation 功能停用也可以提升 NTFS 效能。

註: Vista/Win 2008 以後的作業系統預設是把 8Dot3 功能停用的。

HOW TO
============
Windows Server 2003 and Windows XP
To disable the 8.3 name creation on all NTFS partitions, type fsutil.exe behavior set disable8dot3 1 at a command prompt, and then press ENTER.

Windows 2000 的部分沒有 fsutil 指令
您必須加機碼
您可以使用 reg add HKLM\SYSTEM\CurrentControlSet\Control\FileSystem /v NtfsDisable8dot3NameCreation /t REG_DWORD /d 0x1 /f

Windows 2000 and Windows NT
To disable the 8.3 name creation on all NTFS partitions, use the following steps: Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
322756 (http://support.microsoft.com/kb/322756/ ) How to back up and restore the registry in Windows
1.    Start Regedt32.exe and locate the following registry key:
       HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem
2.    Select the NtfsDisable8dot3NameCreation entry. 
       NOTE: By default, the value for this entry is set to 0.
3.    On the Edit menu, click DWORD. Type a value of 1 in the Data field.
4.    Click OK and then quit Regedt32.
5.    Quit Windows NT and turn off your computer.
6.    Restart your computer and Windows NT.

How to Disable the 8.3 Name Creation on NTFS Partitions
http://support.microsoft.com/kb/121007

在Windows 7中，預設備份還原可以使用的最大硬碟容量是那顆目標硬碟的30%

如下圖：

我的硬碟是300G的硬碟，因此當前最大可用的備份容量大約就是90GB左右。但是這個對某些使用者來說這個並不方便，有可能要備份的硬碟比拿來裝備份的硬碟大很多，但是又被限制在30%，對於這樣的使用狀況，我們可以去調整這個比例的預設值：

請到 控制台->系統->系統檔案保護，在備份的目標硬碟上面點選之後點擊[設定]按鈕：

您可以自行調整這顆硬碟有多少容量可以用來做備份使用

如果您想要透過群組原則來管理無線網路的設定（例如WPA2+AES加密，或是802.1X的設定），並且將這些設定套用在XP、Vista或是Windows 7的話，但在2003 DC群組原則的UI上找不到這樣的設定，該如何做?(如果您的DC是2008或是2008R2，則不需做此步驟)

1. 在DC上，依照http://technet.microsoft.com/en-us/library/bb727029.aspx 中的描述先擴展schema

2. 找一台比XP還新的版本的OS，例如Windows 7 SP1，加入您的Domain。

3. 安裝「遠端伺服器管理工具」。下載點為 http://www.microsoft.com/downloads/details.aspx?familyid=7d2f6ad7-656b-4313-a005-4e344e43997d&displaylang=zh-tw

4. 安裝完後，在控制台>程式和功能裏，點選左邊的「開啟或關閉Windows 功能」，然後勾選「群組原則管理工具」，再按下「確定」。

5. 安裝完後，執行GPMC.MSC，連到DC上，此時就會看到群組原則的管理介面。

6. 當您找到無線網路(IEEE802.11)原則時，右方空白出點選右鍵，就會看到「建立新的Windows XP原則」，這個設定就是for XP的作業系統的設定。而另一條設定就是套用在Vista及Windows 7的Client。

7.再依照您的需求做無線網路的設定。