To perform this procedure, you must be a member of the local Administrators group, or you must have been delegated the appropriate authority.
To turn off Automatic Root Certificates Update:
1. Click Start, and then click Run.
2. Type gpedit.msc, and then click OK.
3. If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Continue.
4. Double-click Administrative Templates, double-click System, double-click Internet Communication Management, and then click Internet Communication settings.
5. Double-click Turn off Automatic Root Certificates Update, click Enabled, and then click OK.
6. Close the Local Group Policy Editor.
Note: You can use Group Policy to set policy settings that apply across a given site, domain, or organizational unit in Active Directory Domain Services.
For more information see http://technet.microsoft.com/en-us/library/cc734054%28WS.10%29.aspx