If you installed SharePoint Server 2010 For Internet Sites - Enterprise using a license key obtained from Volume Licensing Service Center or Microsoft Partner Network before May 25, 2010, you may encounter following symptoms: The following Enterprise features aren't available, or features have reduced functionality: Access Services; InfoPath Forms Services; Chart Web Parts; Excel Services; PerformancePoint Services; Visio Services. NOTE: this doesn't apply to any trial or evaluation versions of the product, and only applies to specific version indicated above.
A new license key has since been provided for use with SharePoint Server 2010 For Internet Sites – Enterprise. To resolve this issue, you must uninstall SPS 2010 For Internet Sites from each server. Then, obtain new SPS 2010 for Internet Sites – Enterprise key to reinstall on each server. Please note that to ensure proper functioning of product, you must reinstall with proper key if you're in this state, regardless of if you're seeing any specific symptoms listed above. Before doing so, it's recommended that you take a backup of your current environment to be certain that you've a safe copy of your data.
More Info: KB2143810