Backward Compatibility between Access 2010 and Access 2007
http://msdn.microsoft.com/en-us/office/cc907897.aspx
Microsoft Access 2010 introduces features that are not supported in Microsoft Office Access 2007. Access 2007 Service Pack 1 (SP1) will not open databases containing these features; Access 2007 Service Pack 2 (SP2) will in some cases offer limited viewing and designing capabilities. Therefore, installing SP2 will help you access more applications created in Access 2010.