Windows7 cannot recognize some DVD drives. This is not a DVD problem, but a Windows7 problem. Microsoft officials have explained that this problem is due to the new power management function of adaptive link power management (alpm) in the SATA driver (msahci.sys), which causes the activation and execution of the alpm function of some optical drives to not work properly, and may not be recognized by the computer.

If your DVD drive happens to fall into this category, please refer to the solutions below.

1. First, check whether it is because Windows 7 cannot recognize your DVD device. Just a yellow exclamation point in the device manager shows that there is a problem with the data signature, or it prompts "Windows cannot verify the data signature of this device..." and so on.

2. There are two solutions:

The first method: modify the registry

Start->Run->regedit->Open the registry Editor, expand in order:

hkey_local_machine/system/currentcontrolset/control/class/{4d36e965-e325-11ce-bfc1-08002be10318}

Delete the upperfilter item and lowerfilter item in the right box item, restart the computer.

Note: When you delete the above two values, the price is that you may lose some functions, such as the CD recording program. If this happens, the affected program must be reinstalled. If the problem persists, you may need to contact the program vendor to see if an updated version of the program is available.

Second method: Command line method

Click "Start->All Programs->Accessories", right-click the command prompt and "Run as administrator".

Paste the following command after the cursor in the command prompt and press Enter:

bcdedit/setloadoptionsddisable_integrity_checks

This solves the problem that the DVD drive under Windows 7 cannot be recognized and cannot be used. problem.