You have a computer that is running Windows 7 Service Pack 1 (SP1) or Windows Server 2008 R2 SP1.
You have an IEEE 1394 isochronous device.
A bus reset occurs, and then you free the isochronous bandwidth that was previously allocated.
You reallocate a bandwidth. Although the allocation succeeds, the amount of available bandwidth shows that the bandwidth was not allocated.
In this scenario, the IEEE 1394 device may not function, or the device may be unable to communicate with a custom application.
An IEEE 1394 bus reset occurs when any change is made to the IEEE 1394 topology.
This issue occurs only when you enable the Windows 7 Monolithic IEEE 1394 bus driver.
This issue does not occur if you enable the legacy version of the IEEE 1394 bus driver.
This issue occurs because of a miscalculation of available bandwidth when the isochronous bandwidth is freed.
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 the problem described in this article. 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, go to the following Microsoft website:
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.
To apply this hotfix, you must be running one of the following operating systems:
Windows 7 Service Pack 1 (SP1)
Windows Server 2008 R2 Service Pack 1 (SP1)
For more information about how to obtain a Windows 7 or Windows Server 2008 R2 service pack, click the following article number to view the article in the Microsoft Knowledge Base:
976932 Information about Service Pack 1 for Windows 7 and for Windows Server 2008 R2
To apply this hotfix, you do not have to make any changes to the registry.
You must restart the computer after you apply this hotfix.
Hotfix replacement information
This hotfix does not replace a previously released hotfix.
The global version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.
Windows 7 and Windows Server 2008 R2 file information notes
Important Windows 7 hotfixes and Windows Server 2008 R2 hotfixes are included in the same packages. However, hotfixes on the Hotfix Request page are listed under both operating systems. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 7/Windows Server 2008 R2" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.
The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
Windows 7 and Windows Server 2008 R2
GDR service branches contain only those fixes that are widely released to address widespread, critical issues. LDR service branches contain hotfixes in addition to widely released fixes.
The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows 7 and for Windows Server 2008 R2" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are very important for maintaining the state of the updated component. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.
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 IA-64-based versions of Windows Server 2008 R2
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about the IEEE 1394 bus driver, go to the following Microsoft websites:
Windows Server 2008 R2 Enterprise, Windows Server 2008 R2 Datacenter, Windows Server 2008 R2 for Itanium-Based Systems, Windows Server 2008 R2 Foundation, Windows Server 2008 R2 Standard, Windows Web Server 2008 R2, Windows 7 Enterprise, Windows 7 Home Basic, Windows 7 Home Premium, Windows 7 Professional, Windows 7 Starter, Windows 7 Ultimate