On a computer that is running Windows Vista Service Pack 1 or Windows Server 2008, when an application tries to obtain an exclusive lock to a volume, the attempt is unsuccessful. Additionally, you may receive the following error message:

Access is denied

For example, when a backup application restores data on a volume, the application may try to obtain an exclusive lock to the volume. In this case, the restore operation is unsuccessful.

This problem typically occurs after the system runs for several hours. When this problem occurs, you may discover that the System process is holding handles to some volumes.

Note: This problem does not occur on a computer that is running Windows Vista without Service Pack 1.

Consider the following scenario:

• You lock and then unlock a Windows Vista-based client computer.
• You try to access network resources.

In this scenario, you may be prompted for user credentials.

Note: This problem does not occur on a Windows XP-based client computer.