When launching Web Site Administration Tool, I kept getting the following error when accessing the Security section.
There is a problem with your selected data store. This can be caused by an invalid server name or credentials, or by insufficient permission. It can also be caused by the role manager feature not being enabled. Click the button below to be redirected to a page where you can choose a new data store.

The following message may help in diagnosing the problem: Could not load file or assembly 'Foundation' or one of its dependencies. This assembly is built by a runtime newer than the currently loaded runtime and cannot be loaded. (C:\Windows\Microsoft.NET\Framework\v2.0.50727\Config\web.config line 59)

Any suggestion is much appreciated.
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