A new compatibility update has been pushed through Windows Update for the English version of Windows 7 RC marked as important. From knowledge base article 970789, the description of the update is as following:
In the English version of Windows 7 Release Candidate (build 7100) 32-bit Ultimate, the folder that is created as the root folder of the system drive (%SystemDrive%) is missing entries in its security descriptor. One effect of this problem is that standard users such as non-administrators cannot perform all operations to subfolders that are created directly under the root. Therefore, applications that reference folders under the root may not install successfully or may not uninstall successfully. Additionally, operations or applications that reference these folders may fail.
For example, if a folder is created under the root of the system drive from an elevated command prompt, this folder will not correctly inherit permissions from the root of the drive. Therefore, some specific operations, such as deleting the folder, will fail when they are performed from a non-elevated command prompt. Additionally, the following error message appears when the operation fails:
Access is denied.
Furthermore, the missing security descriptor entries protect non-admin file operations directly under the root.
The update size is really small, and the changes it makes can’t be rolled back by un-installation either. This is the second important update issued since the release of Windows 7 RC to the public. Earlier Microsoft had pushed out a fix for Internet Explorer 8 for Windows 7 RC which fixed performance issues when opening a new tab. It’s good to see Microsoft actively fixing the OS through Windows Update.