You have a Windows Vista-based computer that does not have an internal USB optical disc drive. Instead, an external USB optical disc drive is connected to the computer.
You run an application that calls the AcquireExclusiveAccess routine in the Imapi2.dll file to exclusively use the optical disc drive on the computer.
In this scenario, you may notice that the external USB optical disc drive is removed from the Windows Vista operating system. When you reconnect the optical disc drive to the Windows Vista-based computer, the operating system does not recognize the optical disc drive. Additionally, a yellow exclamation mark (!) may appear next to the external USB optical disc drive in Device Manager. You may receive an error that resembles the following:
Error 38 (CM_PROB_DRIVER_FAILED_PRIOR_UNLOAD)
Note The external USB optical disc drive can be displayed correctly in Device Manager after you restart the computer.
Service pack information
To resolve this problem, obtain the latest service pack for Windows Vista. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
935791 How to obtain the latest Windows Vista service pack
Hotfixes and security updates that are included in SP2 for Windows Vista Service and for Windows Server 2008
For more information about the hotfixes and the security updates that are included in SP2 for Windows Vista and for Windows Server 2008, visit the following Microsoft TechNet Web site: -
Note:Currently, the list of hotfixes and security updates is available only in English.
A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.
If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.
Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:
Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.
There are no prerequisites for installing this hotfix.
You must restart the computer after you apply this hotfix.
Hotfix replacement information
This hotfix does not replace a previously released 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.
This hotfix cannot resolve the problem for all optical disc drives. If this hotfix does not resolve the problem for the optical disc drive that you use, contact the manufacturer of your hardware for more information about how to resolve the problem.
For information about your hardware manufacturer, visit the following Web site:
Windows Vista Business, Windows Vista Enterprise, Windows Vista Home Basic, Windows Vista Home Premium, Windows Vista Starter, Windows Vista Ultimate, Windows Vista Business 64-bit Edition, Windows Vista Enterprise 64-bit Edition, Windows Vista Home Basic 64-bit Edition, Windows Vista Home Premium 64-bit Edition, Windows Vista Ultimate 64-bit Edition