Jet Database Engine 4.0 Service Pack 8 (SP8) is part of a critical Windows update.
To run Access in sandbox mode, you must first install the Service Pack 8 (SP8) update for Microsoft Jet 4.0 — a program that Access uses behind the scenes for many of its operations, such as running queries and updates. At any time, go to Microsoft.com, click Windows Update in the left column, and then install all high-priority and critical Windows updates.
Before you do this, you first may be able to determine if the Jet 4.0 SP8 update has already been installed on your computer by looking in the Add or Remove Programs section of Control Panel. If you have installed the Service Pack 2 (SP2) update for Windows XP, at the top of the Add or Remove Programs window, make sure that the Show updates check box is selected. If you find the Windows Hotfix KB837001 or KB829558, the Jet 4.0 SP8 update has been installed. You should still install all critical and high-priority Windows updates, however.
Important This update to the Jet engine is a vital part of security in Access and should be installed for every computer that runs Access. In fact, it's part of the Windows critical updates.
Note In order to install the Jet 4.0 SP8 update, you must have Administrators permissions on your computer. See your Office administrator for more details.