After you install or upgrade to Windows 7 or to Windows Server 2008 R2, the DVD drive on your computer is not recognized .
This problem occurs because the SATA driver (Msahci.sys) implements new power management functionality that is known as Adaptive Link Power Management (ALPM). Some optical drives do not behave correctly with ALPM enabled, and therefore these drives may not be recognized by the computer.
The following is a list of some DVD drive models that are known to exhibit this problem:
A supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that is described in this article. Apply it only to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.
To resolve this problem immediately, contact Microsoft Customer Support Services to obtain the hotfix. For a complete list of Microsoft Customer Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:
Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.
To apply this hotfix, you must have Windows 7 or Windows Server 2008 R2 installed.
You must restart the computer after you apply this hotfix.
The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.
For all supported x86-based versions of Windows 7
For all supported x64-based versions of Windows 7 and of Windows Server 2008 R2
For all supported Itanium-based versions of Windows Server 2008 R2
Additional file information for all supported x86-based versions of Windows 7
In the Navigation pane, click Create a power plan.
Select the kind of power plan that you want.
In the Plan name box, type a name for your new power plan, and then click Next.
In the Turn off the display box and in the Put the computer to sleep box, select the options that you want, and then click Create.
Microsoft has confirmed that this is a problem in the DVD drive models that are listed in the "Cause" section.
The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.
Windows 7 Enterprise, Windows 7 Enterprise N, Windows 7 Home Basic, Windows 7 Home Premium, Windows 7 Home Premium N, Windows 7 Professional, Windows 7 Professional N, Windows 7 Starter, Windows 7 Starter N, Windows 7 Ultimate, Windows 7 Ultimate N, Windows Server 2008 R2 Datacenter, Windows Server 2008 R2 Datacenter without Hyper-V, Windows Server 2008 R2 Enterprise, Windows Server 2008 R2 Enterprise without Hyper-V, Windows Server 2008 R2 Standard, Windows Server 2008 R2 Standard without Hyper-V