The File Open dialog box may not work in the 2007 Office system or in Office 2010 on a Windows 7-based computer

When you try to access the File Open dialog box in the 2007 Microsoft Office system or in Microsoft Office 2010, the operation may not work. This issue occurs on a Windows 7-based computer. When you encounter this issue in Office Word or in Office Excel, you do not receive an error message. However, in Office PowerPoint, you receive the following error message:

An error occurred while opening the file dialog. Please save your presentations, exit, and then restart PowerPoint.

The issue occurs if the value of the __COMPAT_LAYER environment variable is set to DisableThemes.

To resolve this issue, follow these steps:

1. Click Start, right-click Computer, click Properties, and then click Advanced system settings.
2. On the Advanced tab, click Environment Variables.
3. Locate and select the __COMPAT_LAYER variable, and then click Edit.
4. Set the value of the __COMPAT_LAYER variable to EnableThemes. Or, delete the __COMPAT_LAYER variable.